You did exactly the right thing. She has no business coming to your home especially after making claims about having sex with your DH. 

I would have liked to hear more that your DH wanted her banned though, after she did that!?

Kids are kids, skids always snitch on you and act as BM's agent in your home. They get rewarded for it by BM. I doubt you will stop that unless you take sanctions such as if you hear that he has been telling BM your business then his electrics will be confiscated or reduced. That might work but it's a hard one to fight. The kid will be desperate for attention from BM who he probably feels abandoned by as he does not live with her like other kids live with their BM's. 

Good for you taking back your rights to a BM free home! 

Does MIL live with you in a house you own, or do you live with MIL in a house MIL owns? 

BM is not allowed in my home. She's been as far as the driveway and thats it.

More power to you. She sounds like a bitch. We banned BM from our house too after we found the bitch in our kitchen uninvited. 

From your last post.. your DH needs to be the one to step up and set boundaries.  BM should not be randomly showing up at your home to see her child.  They should have a set CO schedule.  If that is not possible then at the very least, there should be some stipulated ADVANCE NOTICE PERIOD that she needs to contact at least 24 hours in advance to REQUEST time with her son and to arrange a meeting place.

MIL was not very empathetic to your feelings by having BM over for visits.  I will say that my MIL is a bit like her in that she does try to maintain a good relationship with the BM's of her grandkids... because they are her grandkid's mother.  Now, this can get a bit awkward because her younger son lives in the inlaw apartment behind her house so when his EX comes to see my MIL.. my BIL and his wife are literally 20 feet away.  I think it's rude to basically bring the ex to their residence.. but it IS MIL's home.. so I guess she can make her rules.

As far as the BM.. she may be blowing smoke.. or her and her EX may have been making the whoopie a time or two after they split up...it happens.. but it also isn't anything you need to have rubbed in your face.  She sounds difficult and honestly your DH needs to put a stop to it by having drop offs and pickups done remotely.

Now for the parts of your vent that aren't realistic.  You can't just take the kid and dissapear.  I know the feeling of knowing your life would be simpler without her being in it.. but she will be in your life and so will her son.  If you absolutely cannot get on board with that... then this is not the relationship for you.  If your DH can't or won't set limits on his EX then he isn't right for you either.  I'm not saying ALL limits you want can be put in place but there should be some that are... and yeah.. sometimes pickups can happen at a home and honestly if there was a set schedule of reasonable hour pickups then it wouldn't be as big of a deal because you could plan to be gone etc.. 

And finally, I understand the sadness realizing you aren't a first.. but that doesn't matter if you really will be the last right?  My DH had 2 marriages before me... had 2 kids and we had none together.. he has done things with others that I will never see.. he spent his youth with others.. I am his middle age.. and hopefully golden years too if we are lucky enough to live long lives.  While I do get melancholy about the time I didn't get with him.. don't let that ruin the time you DO have.

Yup did the right thing! Now take a moment to enjoy knowing that the balance of power has shifted! 

Big mental applause for you!

Also: to see a court mediator and make a schedule costs less than 400 for whoever files. That can give dh a reason to say no and to put some much needed boundaries( I speak from experience--I took the christmas money and gave myself a gift of bm1 being legally bound by a schedule and it was the best gift I ever got! DH being willing was just the icing!)

BM unfortunately was given permission from the judge to come get the girls from the house this weekend... BLECK. But ordinarily she's banned form my house as well. It's a privacy thing. BM has made life rather he!!ish. So has her family. I don't need them entering MY PLACE. That's home to me and I expect that to be respected. She already gets to disrupt my life, hurt the skids, cost me hundreds a month and thousands from her debt over the course. She doesn't get my home. I need a place I can relax, and the reality? If my home gets invaded by BM she'll 1) snoop 2) she has sticky fingers and 3) it won't feel as peaceful for me to relax away from all the stressors of stephe!!.

You did the right thing. Good job.

Oh my goodness! When I read this I could so relate. I married my DH a little over a year ago and moved to his home state just a little while after we got married. So, we've been here in our home for over a year. When we first moved here, my DH's ex had occasion to have to drop the kids off. The first time she did, the girls invited her into our home to show her their rooms. I kind of let it pass because I thought well they're excited about their new room and so okay let her see it. Well, she stayed in there for 20 minutes. Then every visit after that, when she would be dropping the kids off, she would walk in with them like it was her home.  She would literally stand in our living room and watch TV, not say two words to the kids or to my ex, just stand there. Several times after that the kids would invite her in to see our new dog, she might come in to discuss school pictures with my ex, and she was standing here like again this was her home. So, after a few times of this, I told my ex I wasn't comfortable with her in my house. He said he didn't want to start anything with her, and that she didn't mean anything by it, it was just her way. I was very hurt because I felt like he didn't want to start anything with her, but he was okay with starting things with me.

I even went as far as to talk to my mother-in-law about it. She said the same thing my DH said, it's just her way, she's a little clueless, but she's harmless. Welll bullshit!!! A few weeks ago the shit hit the fan where my step kids were concerned, and my DH and I had it out. One of the things that came up was the fact that his ex just comes in our house on a whim. He finally promised me he would talk to her. Two weeks ago when he took the kids home, he told me he talked to her and explained to her that it was uncomfortable for me. Her response was that she was hurt, and that she hoped I didn't hate her. I could really give a shit less if she was hurt or not. That's not my problem. I told my DH it's a matter of privacy and respect. This is not her home, she has no business knowing what goes on in this home. She has no business knowing what we have, what we don't have. I told my DH hat he needs to talk to his kids too. Initially when we had this talk, he told me they were too young to understand. I'm calling bullshit now saying that he just doesn't want to have to deal with it. Well, I told him they are old enough now and they need to understand that they need to stop inviting her in here too. They need to respect the fact that this is my house too. My DG has yet to have a discussion with his kids.

Is your MIL living worn you or are you living with your MIL? If you live in her home, she gets to decide who visits. 

Outside that, you and your husband have to decide how to live your life.  I wouldn't allow my husband to ban my kids dad from our home without cause, but that's me.