Stonewalling and my frustrations (I feel desperate for help)

So, I just have to point out I have Aspergers syndrome, and my fiancé has a combination of ADHD and Aspergers. We've been together for 4 years. And I apologize if this post gets EXTREMELY long, but I really feel like I need help here.


Now, whenever I try to talk calmly about issues in the relationship or things he might have said or done that made me angry, hurt or sad, he turns to "stonewalling" and starts deflecting his feelings on me, then storm off if he feels I've "talked too much about it". But I can barely start talking about the issue until he's "had enough" of it! Then he wants us to pretend it never happened. If I try to bring it up anytime after that, he immediately grows cold and distant, then "stonewalls" me again.

He's always been like this, and even used to resort to making his parents "resolve" our issues for us (meaning chewing me out for "not respecting his disabilities" and "not understanding him and his ADHD" or other things I've apparently done wrong that ALWAYS had to do with his ADHD, not even mentioning once that I also have a disability, which for the record I'd NEVER blame on him or "use" as a weapon against him...) And I never told them off, I just silently agreed and promised not to "make him uncomfortable ever again". Yeah, I'm a bit of a people-pleaser.

They don't do that anymore and actually value me as a human being for once in our relationship, but the stonewalling and "fleeing" from arguments, or whenever he perceives something as an argument, still happens. He's just not bringing the parents into it. (Probably still tells them a lot worse things than what actually happened, though, and they're silently judging me...)

Not only is his behavior incredibly embarrassing having to deal with in front of my parents (who don't and NEVER would intervene unless he got violent, but obviously they get worried about me getting sad and upset and trying to hide it in front of them), but it also makes me feel like an idiot for even trying to talk to my fiancé like an adult.

I'm not trying to pin him on anything, I just want to have a normal discussion without conflict like a freaking adult, for Pete's sake! Why is that such an impossible feat to achieve with him?!

He's actually, just now, stormed out right in front of my family when I tried talking to him in private and refused to talk to me anymore. He literally just took his stuff from my room, stormed right past everyone and just left, glaring at me and then shutting the door.

Can anyone please give me advice on how to keep on to my sanity and maybe, just maybe, make this work? I'm really out of ideas at this point.