I am so sorry this experience has you feeling this way.
I am guessing that if you were observing, rather than a part of, this whole thing, you would be a lot more sympathetic towards the players than you are towards yourself. People are usually much more concerned with whatever is going on in their own lives than they are with others. And those who might judge you need to keep an eye on their own inventory, no? Either way, what they think of you is none of your business.
You cannot change the choices you have made in the past. You can only move forward. I hope you don't let fear keep you from seeking the support you need for your own sobriety. Your ex is an adult capable of managing his own recovery, and capable of getting in his own way. I doubt he needs you to do that.
Sending you strength and courage to forgive yourself and move on.