What Bleep said is so spot-on...
Do you attend to Alanon meetings? I think they could really help you. You are so attached to him emotionally. You need to let go. You can't control him.
This might seem like odd advice but it's really very very good. My GF has benefitted tremendously from Alanon (note: she has dated/married alcoholics, almost exclusively, prior to me).
In contrast, I have done a lot of therapy since finding out my xWW's affair.
At the beginning of our relationship, my GF would frequently comment about how I was "doing the 12 steps," which she thought was weird because I had never been to Alanon.
The thing is that dealing with co-dependency issues related to an affair are very similar to the co-dependency issues related to being married to an alcoholic.
So yes you were all right, I was stupid and I am so filled with rage and hate I could explode!!
Seriously: go easy on yourself.
We were all right because we've made the same mistake as you. We made the same mistake as you after people told us the same things that we told you.
This is not easy. You will make the wrong decision often because your emotions get in the way.
Also, be very careful of your anger. As Yoda says, it only leads to the dark side. Going easy on yourself is one way to quash your anger. Letting go of your STBXH and his stupid stuff is another way to quash your anger.
Me: Crap, I'm 50 years old. D-Day: August 30, 2016. Two years of false reconciliation. Divorce final: Feb 1, 2021. Re-married: December 3, 2022.