Hey S, no 2x4's from me. First, your h is lost and in crisis. Does not excuse his having an affair at all. On top of that, he always had honesty issues. So that is why he is acting as he is. He is a mess.
I think you are right in going dim wit him. Get yourself together and your kids through this. He is not your problem. Leave him with his little friend.
Dbing is first and foremost about you. It is about figuring out what things about you that you would like to change, for YOU. It is about finding what makes you happy and strong. It is about GAL and knowing what you want in a relaionship moving forward.
I am sorry you had to deal with all that. I almost feel sorry for the little girl that is with him.
I think you handled yourself with dignity and honesty.
Now take care of you and your children. Let him and his friend blow in the wind.