Read my posts on my thread and JellyBs. Why is this relevant? Because I have the attitude 'this is who I am, it's normal, it can't change, anyone that wants to be with me better accept it'.
The difference is I happen to feel that way about my desires, while being willing to negotiate my behavior and our marital interactions and expectations. And cheating or 3rd parties doesn't play into any of that.
My point, though, is that I don't believe he will ever change. Regardless if you do or not. I think how he's living is so destructive and soul draining for him (you obviously, but him too!) that he wouldn't do it unless he felt it was just 'who he is'. I don't think you leaving will change that, he'll probably feel too defeated, or that he's better off with someone that will put up with him...........like you are now.
PS- time for that new thread!
Me:38 XW:38 T:11 years M:8 years Kids: S14, D11, D7 BD/Move out day: 6/17/14, D final Dec 15