Social freaking the hell out

I'm going to a bridal shower here in about a half hour for a girl that I used to work with.  She invited I think 4 others girls from the store, but everyone else apparently had scheduling conflicts and can't go.  I want to go and see my friend and all, but I am seriously flipping out at the prospect of being in a room full of women that I have never met and having to try to find something to talk about and somebody to talk about it with.  I do not do well in social groups.  Ever.  I don't really like parties, and tend to avoid them, unless possibly if I have at least one good friend to go with me, because then at least I can cling to her like she's a life raft, keeping me from sitting in a corner by myself.  And even then I get worried if she knows other people there and I don't, cuz she might abandon me and go talk to them while I try to tread water and keep from drowning in a sea of self-imposed social anxiety.  Plus I am worried about stuff like, is my gift nice enough/big enough?  Should I be wearing something nicer than jeans and a t-shirt?  Should I go put on a skirt?  I'm thinking it's probably ok.  We're likely to get wrapped up in toilet paper wedding gowns anyway, right?  Damn it I wish this was over with!