I can't recall reading in the big book that it was a good idea to go hang with slippery people in slippery places when you're struggling.
Not trying to change other people's drinking doesn't mean pulling up a ringside seat and getting as good a view of it as possible. Sometimes it needs to just be an acceptance that others will do what they're going to do, and that might be at odds with recovery so we need to act responsibly and stay away from situation that could be dangerous to us.
I reckon that at this point, if I was feeling like a dry drunk, I'd call in sick to that gig and hit a meeting instead.
Wishing you all the best for your sobriety and recovery (both of which only start at rehab), whatever you decide about the party.
BB