I think going forward and since your husband sounds problematic, you could just leave the parties to him.
Take a weekend at the beach instead.
Yeah I know that sounds like WW3, but why is what he wants more important than what you want?
As far as this upcoming party, I don't see why you can't excuse yourself up to your room at any time after the, "activities." Leave the drinkers to fend for themselves - your husband can be in charge of drinking activities. If he's not willing to accept that kind of solution then your problem is a lot bigger than you not drinking.
FWIW, I don't care if people know I used to drink too much and I've quit. They'll think what they want, regardless of the spin I might try to put on it.