"I don't drink"
or, "I choose not to drink, anymore"
or, "not my thing, not interested, no thanks"
Anything beyond that... I mean it's really none of their business.
It took me awhile to wrap my head around nobody needs to know the backstory behind my reasons to stay sober.
And, the people who judge, comment, pry, push booze, or poke fun at you are often the ones who end up questioning their own drinking behaviours.
Just my two cents... Eventually they will quit asking and talking about it.
Today's gossip is nothing tomorrow, they'll find used to it sooner or later.
And most people really don't care. And I hope at the end of the day, you are able to not let it bother you anyone who goes out of their way to make comments about it
you are doing something awesome for yourself! You know what's best for you.