I'm sober, both in the immediate sense and in the sense that I haven't had a drink in 23 years. I know that drinking is not a good thing for me, for many reasons.

If you want to go home and have a beer or whatever - have a good time. If you want to go to the bar later and have a drink - maybe I'll go with you and sip a fancy mocktail or something, we can take turns buying rounds. If you want to get wasted and party all night - have fun, I had a lot of fun nights that way (please don't drive though).

I'm not opposed to anyone else's drinking. I just know I can't.

Teetotal implies an opposition to all alcohol use. A teetotaler is against you drinking. I'm not opposed to that at all, I just choose for myself to be sober, for a myriad of personal reasons.