sarah, if you are that concerned I would really recommend taking a Xanax before you leave. At least you will be able to enjoy yourself. I know you don't like the thought that you have to take it to get through something you once enjoyed, i feel the exact same way. However, I believe I have a choice - I can either suffer through everyhting and only feel slightly better that I didn't take a Xanax (which rarely happens cause I usually end up having to leave early and take a Xanax anyway) OR I can take a Xanax beforehand, not have a care in the world and enjoy it. I woudl take one a half hour or so before you have to leave and if you don't feel it take another. Although one usually does the trick for me, for particularly scary things i take a second an hour or so later.
My husband also helps me to remember that no matter what I am NEVER trapped. I am free to go whenever I want no matter what. This always reassures me. I hope you have someone with you that is supportive that way too.
Just enjoy yourself and take the Xanax if you need it. That's what they are for.