Ex wife in your home.. uh.. NO.. 

I would not back down on that one.  I would clearly tell your husband that while you don't necessarily have a huge issue with his adult daughter visiting your home, you DO have a problem with her being their alone and bringing her mother with her. 

If mom was around, why not use HER kitchen in the home not far away?

I would also tell him that his daughter's story is not entirely truthful because you literally saw his EX in the home and she and the daughter were emptyhanded coming out.  So, the story that he was told was a lie.  If it really was a case of "gee.. mom had to use the bathroom badly dad.. I know you probably wouldn't have liked that she came in... but it was an emergency".. why not say THAT vs coming up with "stories" about some other way they want it to be spun when you saw them with your own eyes.

They live about a mile away with their mum
 

That's the problem 

They think y'all are like neighbors so why not come in and borrow some brown sugar

I always informed the Disneyland dad I dealt with that his kids be lying .... and he knew his kids lied  

Those kids weren't about to lie on me and create serious false allegations that affect my livelihood 

Call out every single one of their lies with irrefutable evidence .... nip it in the bud or they will keep lying even stoop low to lie on you!

Mature response = "Look here Betty and Betty Jr  when I said y'all were welcome in our home that was referring to invitation only  - Bob and I do not allow people over when we're not home. Please respect that or law enforcement will be called and we will press charges for trespassing"

Petty response = Set up some motion activated gun shot audio or rabid dog audio near the entryways. Leave some d!Ldos, whips n chains, nud3 blow up dolls, and seggs swings out in the open. Bet they won't dare have the audacity to traipse into your home uninvited again

*change the locks and/demand adult skids return the house key since they show they cannot be trusted with said house key

Change the locks SD. has no access to your home.  Letting BM into your home is a big NO.  No is a sentence.  DH Not understanding this is a major problem for you.  Time to make DH do re decorating now. He has to paint the inside of the house and buy new furniture.  

If the step kids are 20 and 22 then I definitely agree to rekey the locks. At this age they visit more like an adult guest. If they're coming to visit and see you they can call in advance and arrange visits. You can make it known to them that their mom isn't allowed in your house whatsoever. My ex would never dream of stepping foot into my house and vice versa. It should be like a strangers house to them. 

his 20 year old will randomly stop acknowleging my existance for a month or two at a time. It's a power play, if my husband says anything they will just stop all contact.

They will just stop contact..exactly who said this? Her or your husband? If it's your husband I would give him a firm reminder that if his child refuses to come by because she won't be respectful to you then that is the problem of the CHILD and not your problem or issue. That you deserve respect in your home first and foremost. If his kids don't visit due to that then of well he can see them outside of the house. He can't make his kids rudeness into a problem that affects you. He should demand respect and kindness toward you if he needs to. Doesn't he want his kids to treat you nicely? 

How naive can a guy be? She was there to snoop and that's why both of them were so flustered when they saw you.

1. Check on all your belongings (be as obvious about this as you can) ESPECIALLY your valuables.
2. Rekey the locks and do not give a key to you kids nor his. The same rule has to apply across the board.
3. She is NEVER to be allowed to be alone in your home again because  "if she'll let her mother in who knows what else she'd let past the door?"

Just wanted to add when he says "I don't see what your problem is".. This is a cop out response. He's trying to make issues your problem. The problem is not you. He's phrasing it that way to make you stop talking about it or doubt yourself 

The best thing to do is focus on stating the FACTS. Phrase it is the behavior that is NOT OK.

The problem is that the kids mom is NEVER allowed in our house due to privacy reasons. We need to address this together.

The problem is the kids are being rude to me in my household. This is not ok. We need to discuss how this is a major problem. 

You wrote: My husband thinks I am overreacting and will not see that anyone but me is in the wrong here - he even said, what if she was just using the loo? Go home and use your own lady! She has never so much as acknowledged we're married but now she can come into my house when I'm not there and have a look around?!!

Men like this? They don’t see a ‘problem’ until it smacks them square in the face—that’s the level of narcissism we’re dealing with. How do I know? If you’ve read any of my blogs, you’d already know the results of my DH keeping his head shoved up his own ass or the skids’ for years. Spoiler alert: it’s not good!

Based on your BM’s actions, she is definitely NOT your friend! There’s an unspoken, universal law in StepHell: behind every rude, dysfunctional, and mean-spirited skid that hates their stepmothers, there’s a manipulative mastermind pulling the strings—a cult leader, if you will—the BM, lurking in the background, working her magic. You think the skid's behavior is random? Think again. It's all covertly orchestrated or promoted by the BM as the puppet master.

BM’s and Skids’ Spyware

I would suggest you check your place for any planted listening devices or hidden cameras. YSD, Crazy’s little spy, had a nasty habit of recording us, and of course, DH, with his head so far up YSD’s behind, would defend her with the usual nonsense: “She’s harmless,” or “She’s so innocent” (gag!), or the worst, “She doesn’t know what she’s doing” (barf, again!). That is until she caught DH (Daddy-cakes) lecturing her on tape and YSD ran straight to her cult leader, Crazy, who called CPS on him. And that’s when DH, who’d been screwing around for way too long, finally found out just how bad it could get.

Poisons

Another thing to check? Your food or anything you consume. If BM knows your allergies or health issues (via the Skids, or your dimwitted DH telling the skids all your business), don’t be surprised if something suspicious shows up in your meals or your medicine cabinet or condiments or pet food. You end up in the hospital or worse, and suddenly, she’s collecting a big inheritance through the skids. Sounds far-fetched? Trust me, with people like this, you can never be too careful. When DH's oldest feral was just 14, she was already trying to get the ‘creature’ she was ‘dating’ to beat DH up. It's unbelievable, but that's what we were dealing with when we had that level of dysfunction at play—scheming skids raised by manipulative BMs, willing to assault their own father. Keep your guard up, because there’s no telling how far they’ll go. Can you truthfully say that you would put your life in your skids’ hands?

Enjoy Your DH’s Ass-beatings when they happen

My DH never changed a thing, no matter how bad it got. In his world, I was always the problem. Why? Because he was too terrified of BM and the skids, and the constant threat of their manipulative blackmail. The usual line was something like, “Daddy-cakes, if you don’t let us torture Toaster, you’ll never see us again, and you’ll end up paying more child support—oops, I mean ex-wife support.” He lived in fear of upsetting their delicate little world, so he clung to the strategy of “see no evil, hear no evil,” and that meant he definitely wouldn’t ‘speak no evil’ to his precious crotch droppings.

He was so wrapped up in avoiding their wrath that he refused to stand up for me—or himself. It was like living with someone who thought if they buried their head in the sand long enough, everything would magically fix itself. But that’s not how life works, and I was left dealing with the fallout.

So, I decided to disengage, citing "health issues" as my reason, while in reality, I was stepping back to preserve my sanity. DH ended up bearing the brunt of their manipulations—an abuse he brought upon himself because he refused to confront it head-on.

A prime example? BM and OSD invited DH to attend OSD's homecoming, claiming she had been elected homecoming queen. This, after two years of estrangement and bitter court battles where DH got his ass handed to him. I could see through the manipulation, but DH, ever desperate for approval, couldn’t resist the bait.

I told him straight up, "I’m not going to ‘worship’ at OSD’s shrine. You can go alone if you want, but I wouldn't if I were you." It was so typical of BM and OSD to dangle a bone in front of him just to keep him on their leash. But by then, I had learned to say no to the toxic drama.

He didn’t go in the end, but, of course, he couldn’t resist watching the whole thing unfold online. And it became painfully clear—he was never meant to be anything more than a bystander. Had he shown up, they would’ve humiliated him by refusing to let him walk onto the field with BM to crown OSD. The kicker? They didn’t even bother to tell him he needed to dress in formal wear, probably just to make sure he’d wouldn’t want to walk out on that field with them.

They didn’t want him there as part of the celebration. They wanted him in the grandstand, sitting quietly in the background, looking on as an outsider—just another distant spectator in their pre-planned spectacle. His presence wasn’t about love or family; it was about control, about keeping him on the fringe, reminding him that he didn’t belong. And watching it all play out online, he finally saw it for what it was—a cruel game he was never meant to win.

The real kicker? OSD's acceptance speech at another event, probably a day later, which DH also watched online but didn’t attend in person. It was nothing more than a sickening display of ass-kissing towards the Golden Uterus, BM. OSD stood up there, claiming that BM was her "only parent" and the one who "raised" her and "stood by her side as her best friend." DH played the speech for me, and I couldn’t believe the level of groveling OSD was doing. It was like a cult worship service, with BM on the pedestal. It was a direct snub to DH.

I’m sure, if OSD ever dupes some poor fool into marrying her, DH will get an invite, not out of love, but so they can set him up for another public humiliation.

I’ve come to realize that the manipulative humiliation my DH endured was, in a twisted way, a blessing in disguise. It was the only thing that finally made him ‘see the light’ and start to change. For years, I would tell him exactly what was going to happen, predict every move BM and the skids would make, but did he listen? Of course not. He was too wrapped up in his guilt, fear, and obligation to face reality. Life had to be the one to knock him down, and honestly, it worked. I think he was too terrified to go to the Homecoming events alone, these men are such cowards.

Sometimes, you’ve got to step back and let the drama play out. Let BM and the skids serve up the consequences. It might feel cruel, but the truth is, it’s often the only way they’ll learn. You might even find some relief in knowing that those tough lessons—delivered by the very people they were trying to please—are exactly what it takes to open their eyes. You might just have to learn to sit back and let it happen, because in the end, it’s that ‘ass-beating’ that could be the catalyst for real change.

What happened was a HUGE nope.

Oh Hell No. BM in your house is a hill to die on. It's bad enough these b!tches are always skulking in the background of our lives. They don't get to skulk around in our HOMES. If your DH won't back you up you may have to deal with SD and/or BM directly. 

Time to play the nuclear option. Re-key the locks and make sure that no one but you and DH have a key. Better yet, get a bio-lock that reads finger prints and only you can register users.  And.... Web cams with a full security system that trackes any entry, exit, etc.... That way you do not have to have the idiot parent of toxic spawn fights with your DH over his failed family baggage.  Web cams with a large storage drive and you can give daddy clarity that even his delusional pea sized brain can recognize.

When he plays the "you wouldn't care if it was your kids" bullshit you need to immediatley jerk an knot in his tail with "my kids would not welcome my X into the house".

As for his XW "using the loo", that is one of the ultimate violations of the sanctity of your home. Who wants his XW's stanky ass on their toilet and her washing her nasty flea picking monkey paws in your sink and drying them on your towels?  Toss your toothbrush and get a new one. These types tend to do juvenile evil crap. Err on the side of caution for sure.

As for "just  helping to carry out the baked goods"...my ass!  XW/BM was casing your home and she and her rancid crotch product were up to no good. I have no doubt.

That your DH is without clarity or a single functioning brain cell on reality regarding his failed family baggage is beyond infuriating I am sure.

Take care of you.

Just my thoughts of course.

I hope that you find this to be a good place to vent, contribute, and to pick up some useful advice and perspective from others who are living the dream of the blended family adventure.

Take care of you.

By letting BM in your home. And lie to you and DH.  ADD ring cambers on all doors.  To see who is coming into your home .  Don't let your SO bull $hit you about you are not normal to care about BM in your home.  Again make sure to change that lock SD could of made a copy of the key .  
'You have to make DH Understand how violated you are having BM in your home. I would be trowing a fit over this. 

Welcome to steptalk.

Yes, thats a huge boundary violation. You dont invite strangers in (to you BM is a stranger) when you are a GUEST in someones home.

Yeah, gaslighting you with "its a YOU problem"...nope nope nope.

BM doesn't even ring the doorbell when she picks up SD14. She waits in her car on the curb and texts that she is here. Like she should! No need for her to be on our property.