Supportive.

I set rules like "I will only eat some cake if directly offered" I will only eat on these preset days (my birthday, my wife's birthday, my anniversary, holloween, thanksgiving and Christmas).

If I know that I'm going into a sugary (a party) situation I'll look for thing that are naturally sweet like fruit instead.

I limit myself to one or two bites of sweets if I'm obligated to eat something sweet (like cake at my nieces birthday party, and grab the smallest piece available).

Also make sure to tell all your friends/people you eat with regularly so they can be supportive.

Also, it's likely your tolerance for sweets will diminish. One time I binged on sweets about 6 months in on my birthday and I got so sick from it. I just remember how bad it made me feel and it helps remind me how bad it is for your body to spike your blood sugar like that. That really helps me keep things in perspective.

You'll probably also find that after a while you won't like sweets as much. Things will likely taste "too sweet".

But really, tell people you don't eat sweets and why. Most will be really cool and supportive/ helpful.