Have you also considered discussing the triggers with your friends, or would that be to far removed from social norms?

I just noticed I never responded to this part. I've discussed it a little bit; some people know enough of the history to already understand what's going on, and some I've explained it to because they asked and to get it off my shoulders. Someone offered me a good metaphor for it:

People restrain our behavior in front of strangers. We don't talk about very personal things, or very suggestive things, or very nitpicky things, because we don't know how they'll react. As we get closer to the ones who become our friends, it becomes more okay to open up and share more.

What happened to me is as if that switch got reset, but only on my end--so I became really uncomfortable seeing and hearing things that my close friends had every reason to believe I'd be comfortable with. I really didn't want to ask them to treat me like a stranger! That seemed more likely to damage the relationship in the long-term than just backing off for a while would.

It's gotten a little bit better recently; I'm working on unwiring the trigger that makes me want to back off so much. This involves some trial and error, but at least it's progress.