Zenchaser, seriously, I think you are waaaaaaaaaaaaaaaaaaaay overthinking this!
Trying to outguess everyone's reactions around you, figuring out what their next move will be, their opinion of you, etc etc etc.
Just be yourself and do and say what seems natural to you in the moment. Whom to tell? Just let your instincts in the situation tell you what to do...you might be surprised how little "normal" people care about your non-drinking.