There is a light at the end of your tunnel. You don't happen to see it at this point because it's covered up by the anger, by the disdain you have for your wife.
AJM has laid it out for you. Take the high road, do what is necessary for your kids. He can show you the map but.....he can't walk it for you. I have been there as well similiar to AJM. I can look back and say it was hard but now looking back it was worth it. My kids see the lessons they learned from it. I didn't even have to tell them. THEY SAW IT FIRSTHAND.
BE THAT GUY!! DAMN, you so hard on yourself. I get it that your wife is a nutjob. I had one too! but.....you put to much power into her actions! Only you can take that power away and put it back into yourself.