So does he only gaslight you when it comes to your personal medical information, or does he gaslight you about everything?

A child has no business knowing about your personal medical issues or any other "adult" matters. Why on earth does your soon to be husband think his son HAS to know about your medical?

I would be mad as hell if I was you.

Sharing with a 12 YEAR OLD??

Expect this to be the rest of your life with this man. If you are okay with everybody in town knowing your medical issues, personal business, preferred sexual positions, and the type of underwear you like, stay with him. Your fiance has ZERO respect for your feelings and your privacy.

RUN for the HILLS!

you have been warned.

I'm not sure why he is telling the 12 year old your personal businesss in the first place. He is So in the wrong there. If my Dh EVER told my SS something personal about me - I would flip out on his ass. 

I would hate it.

I've had a difficult career since I married and I've been on a thousand job interviews for jobs I never get. I've begged with my husband not to tell anyone in his family because I'm ashamed and I think some of them would enjoy knowing I'm failing.

Perhaps you've already done this, but you have to make it very clear to your husband just how serious you are about the information block. You might have to flip out, have a tantrum, raise your voice, make a scene for your husband to "get it." Even now, he's making rather light of it instead of apologizing as he should.

In fairness, if your SS knows about your health by sheer virtue of being in your house, and then he tells BM, I'm not sure how to stop that flow of info. He's a kid. He's not necessarily going to get it, and pointing it out to him might actually alert him in another way you don't want (he might wonder what the secrecy is about, what's up that you all don't want out there, and start listening closer to what's happening in your house). But if he's asking your husband questions, your husband needs to not tell him anything. Period.

You have to realize in normal circumstances, people you aren't friendly with wouldn't ask about personal health. So either BM is nosy or she's trying to show you civility by asking about your welfare. Only you know which it is, but don't rule out has asking to be kind unless you're sure it's otherwise. And if that's it, try to take it in stride. You all are joined whether you like it or not in a very weird way -- through a 12-year-old. That's so weird when you think about it, what are the boundaries? You're trying to set some, and that's good, but if they all came from a family that is more open and less private, it will be hard for them to understand your point. Some of this comes down to our original family dynamic -- that is, the family in which we were raised. So to that end, step lightly in trying to make these boundaries.

Your fiancé is an ahole & I’d seriously be rethinking walking down the aisle.

Your DH is being nothing short of abusive. Your FSS has no business knowing anything about your medical history, and your DH has no right to discuss this with him. He’s gaslighting you, not to mention behaving like an absolute child. 

Why he feels the need to discuss personal issues with a 12 year old is beyond me. But if you’re not willing or interested in having your personal information shared with your skids or BM you should reconsider this marriage. He’s an a$$.

I would not marry this man. He is giving your private medical information to a 12 year old? A 12 year old who obviously can't keep it to himself? This man has no respect for you.  And then he takes an attitude with you? Nope, that would not be the situation for me.

Wow, why does your fiance think it's okay to share your personal info with his 12 year old son, of all people? What a jerk.

Then, he takes it to the extreme when you ask him not to talk to his son about your issues? He won't ever tell his son anything about anything? Does he realize how ridiculous he sounds? I mean, he doesn't have anything to talk to his kid about, other than your medical history? How pathetic.

I don't even know how to wrap my brain around this.  Is it only your medical information that's up for discussion? Or is your salary? Your mortgage? Your savings account? Your credit score? Your insurance? Your will?  Your retirement? Your weight?  Your bra size?  Why is anything about you fair game for your SO to gossip about with anyone? 

That aside what in the world is going on with the other half of this hot mess? Is your SO seeking out SS as a confidant? Is SS asking pointed questions based on what he's experiencing in the home? Is he asking pointed questions for some other (cough) reason?  Is he asking generic questions and your SO is a gossipy teenager? 

I like to think it wouldn't happen once in my situation because neither SO or myself are immature clowns but let's suppose I'm wrong there and it does happen.  Once.  There would be no second time. 

That you are on round number three and your SO is being a whiny entitled brat about what he can and cannot share with a third party, nevermind that third party is a CHILD, is beyond absurd.

Recognize that if your SO sees no issue with it, cannot even pretend to understand where you're coming from, this will never stop.  It'll be SS or maybe MIL (or some other inlaw) or the neighbor or a coworker.  It'll go on and on and on until he gets it and decides to change.

Don't sit back and wait, marry him, thinking you can change him.  The path it will take to discover you can't will be more damaging than BM (or anyone else) inadvertently ratting him out for his betrayal of your confidence.

Oh no! I would make it very clear that my private life is just that, private!

Either he gets that or you no longer share details with him. 

SS is 12. He doesn't need to know the details of your medical problems. Even if it were your biological child, details at 12 are inappropriate. 

Ask DH if he were to start medication for bedroom performance problem if he'd be ok with you sharing that with his son.

I'm trying to picture this:

DH: Hey son, SM has some excessive bleeding and lots of pain with her periods, cramps and giant clots, too! The doctor thinks her endometrial tissue has actually moved into her bladder, and wow, does it bother her.  They might even have to take her entire uterus out! You know, they go through the vagina now, so it's not quite as intrusive.

SS12:  Ewww. *dials phone to call BM*

Most grown men I know don't want to hear about lady issues, WTF is he telling a kid about it for?

From now on DH hears nothing about your medical issues. That is, until you divorce him.

Just when I think I've heard it all I get slapped again with another......wow!

My DH’s family overshares too. I made it clear to DH that my business—especially health, money, and marital issues—are none of their business. He has respected that, except for one time. He will never make that mistake again. 

Your DH has not respected your wishes. Somehow sharing with his kid is more important than honoring your privacy.  

Your eyes need to be wide open. Are your thoughts, feelings, needs, wants dismissed in other areas? Does he throw little (or big) mantrums when he doesn’t get his way? When the two of you disagree on something? When your wants and needs are different from his son’s wants?

I'd like more information about your stbh.

I'm curious about his medical issues, personal business, poor money management choices, bad breath, preferred sexual positions, the type of underwear he likes, whether or not he has gas, the color and frequency of his bowel movements, how overweight he is, how below average his junk is, how often he fails to get it up, and a detailed account of all his below average sexual performances.

Surely he wouldn't mind if you shared that information with us, would he?

This man has no empathy.

Your fiance has elevated his son to adult/peer/partner status therefore keeps him in the know about what goes on in the house, INCLUDING what is happening inside of your lady parts.  They are enmeshed, it likely started when SO and BM divorced.  Many divorcees, men and women begin to treat their oldest child as a spousal replacement when their partner is no longer in the picture.  

SS is always going to report things to BM. This is why adult conversations are not privy to the kids.  Having skids in the house is like being under constant scrutiny and surveillance.  My bios will also report EVERYTHING to their dad (exH), but I don't share everything with my bios.  I dole out info on a need to know basis.  They are kids and should be focused on kid things not my adult drama and issues.  I feel sorry for ss that his father feels he has to share what is going on with your very personal issues.  I mean what 12 yr old boy wants to hear about that???  

I can only echo what everyone else has said, really think about what your roping yourself into.  This guy is not supportive of you but more worried about his sons feelings.  

I’d be SOOOOOO tempted to get even. 

“SS  - just wanted to update you on your father’s erectile dysfunction - you know his limp dick problem.”  And then give dates, times; etc.  Who cares if you’d have to make it all up. 

I think it's unfair to ask a 12 yo to keep secrets from his own mother. While you may have raised your kids not to say anything outside the house, he obviously hasn't been raised this way. He may not have realised it was private. And I'm not clear what the secret was - did he say "JG23 had to have a uterine ablation and yatta yatta yatta?" Or did you have surgery which impacted on SS - as in you were in the hospital or outpatient or recovering while he was there so he would have known about it. 

If it was widely known inside your house that you'd had surgery and the basic nature of it, you cannot expect that to be a secret from BM. I have a BS who is almost 12, if I found out that my son was being told not to tell me something, I would NOT be happy. That doesnt mean I would need to know the details of things (frankly I wouldn't care), but that would mean someone was trying to interfere with MY relationship with MY son and teaching him that it's ok to keep secrets from me or even lie to me, which is 100% not ok with me. It's also a terribly awkward place to put a kid.  

Your boundaries of privacy as well - are super different to mine. That's ok because we don't live together. But what I'm saying is that I found your boundaries of privacy a bit odd as you would probably find mine a bit odd - but both of them are ok if that's what they are. So when you live with someone if this is an issue that's important to you - you need to let them know and find a way to deal with it that doesn't end up making a kid lie to his mother. It's also ok to have a conversation about how you would prefer that he not talk much about it because you feel sensitive about it - but don't forget this kid has the right to tell his own story - even when it involves you. 

That being said, it sounds from your description like your fiancé doesn't deal well with criticism and blows up rather than trying to see it from your point of view - and that's a red flag. I know because my son's dad was like that and I endured many years of hell and walking on eggshells. And it's also not clear from what you wrote if dad was saying waaaay too much to this kid - basically enmeshment and inappropriately confiding in a child - or if he was sharing only appropriate details and you're unhappy that BM knows about it at all.