Hi, Bjo! My birthday is the 11th, too.
I have to agree w/ the others who say that you should avoid the party. As to what to do w/ yourself on your b-day, I don't see the harm in going out to hear live music-- but find some place that has artesean non-alcoholic beverages. That way you can have a fancy drink w/o having any alcohol.
However, if a bar/venue that serves alcohol is going to be too triggering (and it sounds like it might be), then my fellow posters above have already offered up a good quantity of suggestions. Hang in there!