Thank you so much for your perspective! It's really helpful. I suffer from pretty severe anxiety (general and social), so I understand some of what he goes through, but I cannot begin to fathom all of it. My FIL is going to call me in a bit to discuss things with me. He still doesn't seem to understand why BIL makes me and Steven so uncomfortable when he's like this, especially with a big event coming up. I want to stress that a) we don't want BIL to be any more stressed out than he needs to be, especially around so many people and that b) selfish at it may be (although my wedding is the one day of my life where I feel I get to be selfish, to an extent), I don't want to be worried about BIL causing a scene or having an episode that scares or harms other guests or myself.

Like I said, I have severe anxiety. When BIL was having a hard time a couple years ago and Steven and I had to bear the brunt of it, I had to start taking medication and began seeing a therapist. I'm starting to feel myself getting back in that place again, and dammit, I just want to enjoy my wedding!