Dude!!! Don't do it!!
I threw away 30+ days sober on a wine tasting trip to Napa back in January. It was organized and paid for by my girlfriends for my birthday in the November, and I thought I could do it without caving in. I lasted 7 hours. And it was 7 hours of torture for me. I didn't get drunk that night..or the next...or the one after that, but it was enough to slip WAAAAY back into the clutches of my beast, nearly ending my life 3 months later.
I know if I hadn't gone - yes, I would have been worried about disappointing people, yes, I was worried about hurting their feelings, and yes, I would have been pretty ****** to miss it, especially if the pics were going to be all over facebook (which they were). I just know that if I hadn't gone, I wouldn't have slipped back into what was nearly the end of me. Your call, obviously, but I really think you are dreading it
P.S I know how you feel. I am a 38 year old Mom - and not one single one of my friends aged 35 - 55 don't drink. I am the ONLY one. I hear you!!!