Learn and move forward. No one had more regrets than I. If you read my sitch you can see I was one, mean, ornery, jerk of H. My W had every right to leave me. But here is the thing, we can't change the past. We can ask for forgiveness but we can't change what we've done. We can however resolve to do better from this point forward.
There is a line from a Bon Jovi song called I'll Be There For You. It is: "I can promise you tomorrow, but I can't buy back yesterday."
Regrets are like anything else. You can let them paralyze you, or you can use them to better yourself and move forward a better person. THAT is 180ing. Becoming a woman, and a wife, only a fool would leave.
You are constantly worrying about your sins of the past. You are constantly taking your H's temperature. You are constantly worried about what may come (S and/or D). You can't change the past. You have no control over your H. And you certainly cannon prevent S or D if he is intent on going through with all of that.
So focus on what you can control! What are your GAL plans for tonight? For tomorrow? For Sunday? How are you going to be better today than you were yesterday? You mentioned exercise, better eating, losing weight. Put that plan together. Get into IC. Read books like there is no tomorrow. And the work on detachment. I tried to mention this to you earlier. Become cool as a cucumber. You need to get to a place where he could come to you and confess having an orgy with 10 women, and you would go: "Oh. Ok." and go back to what you are doing. (Detachment doesn't happen overnight so work at it!)
Focus on you. On being busy. On learning and improving. On not letting his crazy affect you. Become the best you can be!
"What is best for my kids is best for me" Amor Fati Link to quotes: https://www.divorcebusting.com/forums/ubbthreads.php?ubb=showflat&Number=2879712