Could you maybe step outside if things get too overwhelming? rather than other crowded parts of the building. I haven't had a situation exactly like this, but I've had times I've agreed to do something I really am not up for or that I really find too overwhelming at least at the time...but then I feel obligated because I said I'd go or whatever. So aside from stepping outside, maybe even going for a short walk to get some space during the event or whatever I also try not to obligate myself to activities I am not sure I'm really up for.

Perhaps its best you talk with your wife/family about this issue and explain its no offense to them but that crowded events like this make you feel sick so in the future you'd prefer not to participate...though don't know how accepting they are of your sensitivity in this area.