PNM, I agree with Melinda that you don't have to go into great detail with anyone about not drinking, nor use the A word unless you want to. You just have to say you're not drinking any more, and you'd really appreciate their help. Nothing easier than mixing OJ with soda water rather than champagne.
If it helps you that they know, then just tell them. I predict you'll be surprised how much more relaxed you'll feel going to any event knowing in advance you won't be drinking.