You can't fix this on your own. The only way this marriage could survive is if she's willing to pull her weight into improving this situation. I don't think she will.

You seem like a decent guy, maybe it's time to let go and move on. Let her go, where ever she wants and keep the kids. Why should you pull all the weight? It's a wonder your on your last string of hope. I would be too.

If you feel it's time to do something then do it. However you act is not the point, act the way you feel. I'd be %#@&#! as hell if I were you. Her mental illnesses can't justify having affairs.

I hope all works out for you and your kids.