I wouldn't bring up the affair because all it does is make him more defensive and angry. I would leave that alone for the time being. Whatever you know, keep it to yourself for now. I know that this hurts, but the more you focus on her and what he's doing w/her, the more he'll defend her and side w/her as to the reason for leaving you. Besides, most of they lie about the affair even when confronted w/the evidence.

I want to point out that if you were doing things the first time around and then stopped, yes, I can see where he might think it's a ploy to get him back. However, if you remain consistent w/your activities and continue to do them no matter what he says, he will eventually see that this is something you are doing for you. The key is consistency.

For now, focus on you and your family. Continue to do things for yourself and leave your man/child swinging in the wind.

Sit quietly, the answers will reveal themselves when you least expect them to.
The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.