You are NOT going to give up. You've already been through the worst of it but you fought your way back and you have found your strength.
So you had a "setback" we all do. Boy I certainly had my share. Nobody here is going to fault you for that. What I do know is that this woman is in noway better than you. She was your friend. What kind of friend does this? You know projection is a funny thing. It keeps us from dealing with what we have done to cause this kind of pain to the people we love. Your ex said what he did because he was projecting all of the things he hates about himself. You're not crazy, far from it. I remember onetime I was having a talk with my H after he left and I started to cry. He said, "look at you. You need to get some help". I believed that, for a while, but I was the one who could still feel emotion. That is way more normal than hardening ones heart and feeling nothing. Would you want to live like that? Wouldn't that be an awful thing for your children? There is NOTHING wrong with you except for the fact that you love your ex and you're mourning the death of your family as it was. We all know how that feels.
The good thing and the silver lining in all of this is that everytime they show us this side of them, it makes us stronger & helps us to detach.
Donna, he has to live with what he's done. Maybe, at least for right now, he can hide behind this relationship and justify it as his happiness. At some point he'll realize that he's still empty and no other person will ever be enough if he doesn't believe he is emough!