I've read bits and pieces of your story. I spent a good 6-8 years living with mine in the house (can't really even remember when it all began, suddenly there was just an emptiness there), doing everything and anything to keep him there "for the kids."
Finally, with the disclosure of a long affair and then carrying it out in my face and the coldness and nastiness to me and the kids. It was too much. I kicked him out. Came home one day and he was here. Gave him another chance. He blew it within days. One of the kids finally said I had to make him leave.
We've all been so much happier since he's gone.
I'm still not out and through, but I know now that my days are what I make them. I know that he can only destroy me as much as I let him. I know that the stupid things he does to remind me that he is still there are a sign of his disordered behavior. They aren't love, they aren't caring. There is no hope there.
I guess I don't understand why you are living like this and how you think it is good for the kids. If he is a good dad now he will probably be a better one away from all the drama and pain.
As I see it, you have two choices: 1) leave or kick him out; 2) decide that you are not going to let him and what he is doing or isn't doing define your happiness any longer. Remember, you can either change your situation or change how you feel about it (but only over the parts you control).
Both of you seem determined to gut it out. For what? Why are you letting him hold you hostage?