Penny, I see one positive, at least your H admits he is screwed up. The only thing my H has ever said was I guess it was my fault I should have talked to you more, but other than that he doesn't admit he has any faults. So maybe your H will see the OW for what she really is. My advice is don't point out any more negatives about the OW, somehow she will turn it back around on you. Let him discover things on his own. Go semi-dark on him and see what he does. Things seem to be a little better for you than me. I know that sounds odd, but he does seem to have some remorse, mine doesn't.
I identify with your sons asking you why you stay with him. My oldest D too has at times told me to quit putting up with him. I didn't deserve to be treated like that. She was really mad at him, but never really let him know it. As a matter of fact an old boyfriend from high school started calling me and checking on me. He called one time and she answered. I explained who he was because I didn't have anything to hide. She said why don't you go for him Mom? I said number one I'm married and number two I'm not interested. Now she seems to be on better terms with her dad. Youngest D doesn't say anything about her dad good or bad. She just doesn't have a lot to do with him, unless she needs something. She relies a lot on me. She used to be real independent and didn't share feelings a lot. I guess the one thing that has come out of this she opens up to me a lot more now.
Life's challenges are not supposed to paralyze you, they're supposed to help you discover who you are. -- Bernice Johnson Reagon