Ohme, it sounds like you are going to go to the wedding, I hope it will turn out well for you. I also went to a wedding while trying not to drink and I did succeed. I was seated with people who were not close friends, some people I had never even met. They offered me wine and instead of saying "no thanks" I felt like I had to give an excuse (of course I didn't, 'no thanks' would have been sufficient for people I hardly know) I said "no, thanks, I'm on a round of antibiotics"
It sounds like your close friends are going to really push you on this. A wedding reception where they are all drinking, and the focus should be on the couple- is not the place to get into your decision to seek sobriety. In that moment I'd use the doctor excuse as Ronker suggested above. "We'll talk more at another time, but my doctor is concerned about my liver and I need to stay off alcohol for a while" if they push "honestly, now is not the time, we'll talk later and I really would appreciate not being pressured to drink, it is hard enough as it is"
You then, at a later time, really are going to have to talk to these girls. Peer pressure is not part of a healthy friendship, particularly once you get beyond the teenage years and particularly when it comes to something so serious.
Play the tape through Ohme, think of the ridiculous dancing around the room, the hushed whispers of "poor girl, what a mess" the smeared make up and slurry words. Think of that professional photographer who could get a great shot of sober you and your husband. Or he could get a short of a sloppy mess, hanging off the chair or making some stupid and inelegant pose.
Please do come back and post.