I can't be around my boyfriends parents or be at his house

My situation's very different from yours but I'd still like to share what I did wrong. This girl had been my friend since the 3rd grade. Just a really good friend who helped me whenever I had problems with my own uber strict and conservative parents. She was also the first person I came out to, as Bi then, (I was unsure).
But things turned ugly for her from High school. Her father walked in on her and her boyfriend kissing and that completely ruined her relationship with her parents. They became very, very strict and unreasonable and she'd come to school just to cry and get away from the mess at home. We're family friends so I visited her house often and one day her dad slapped her because she flunked one physics assignment. Right in front of me. I'd heard stories but this sent my blood curling and I went and defended her pretty aggressively.
The next day, she seemed normal, as if nothing had happened to her, but I kept bugging, trying to help her, thinking I could. I later realised that even with the constant emotional abuse, she was still on her parents' side, and considered them victims rather than culprits. Yet I stupidly continued criticising them. She eventually snapped and called me a bunch of hurtful stuff (things like f*g). I backed off, but I still visited her house a couple of days later. My face triggered her parents' anger but strangely hers as well.
She outed me then and there. I was in shock but still managed to laugh it off as a joke and somehow left. I haven't talked her since, and the worst part is, that I don't feel bad for her anymore. Wrong as she may have been, she was a really precious friend and there isn't a day when I don't regret what I did.

I could only suggest you continue to maintain a safe distance with them. Your relationship is obviously the most important thing right now. Avoid anything that you think could trigger a breakup because I think you'll not only feel hurt but also guilty if that happens. What I've seen happen with my sister is that kids become really independent in university and start relying less on their parents. It'll definitely happen to your boyfriend, even if to a lesser degree. And so he'll be less bothered about the lack of communication and contact between you and his parents. This will never completely solve the problem. At most, you can give it a few more shots and if you still can't tolerate them, then get used to being uncomfortable with them. It sounds rough, because it is. The one thing that'll keep you going is how much you love him and how much he loves you, and that's precious.
All I can is that if you're smart about it, it'll get better. It always does.

 

My situation was nowhere else near as intense as yours. But to avoid these feelings, I simply stopped thinking about what I'd done and focussed my other friends, exams and my other commitments.

Your anger, stress and anxiety probably stem from you feeling helpless. How you feel you can't change your boyfriend's family dynamics without making everything worse. You'll really have to give up thinking you can do anything to make it better. Now it's all about damage control and preserving the relationship you already have. And I don't know anything about you, but I'm sure you've done nothing to be guilty for. Your first priority is your boyfriend so you're just looking out for him. After all you're dating him, not his mother.

As for meeting them, take it as some tough challenge and reward yourself if you succeed.Try your best to control yourself, fake your best smile, talk about random topics and look at them objectively as a middle aged couple you're trying to talk to. If you do end up saying something, tone it down with some reasoning and change the topic. Remember the more comfortable they are with you, the more you can influence them to change how they treat their kids. Right now to them you're just some person who's dating their son but doesn't like them. And you've got to change that.

Your panic attacks sound serious though. This might not be the best time for it, since you're leaving for university, but try to contact a therapist for it. Those things prove damaging later on.