I totally agree that the "stuff" is about control. I agree that you should not let her control you anymore.
I do not think for a second that you should doubt that you did everything you could and are a great dad. She, just like mine, is selfish and trying to use any method possible to maintain power. They know us well, and will try to use whatever method that they think will work. Yours is trying to manipulate through the kids and finances. Mine is trying to use guilt and my conscience.
You need to hang tough and try to ignore the bullsh*t. That's what I'm trying to do.
As far as the dating, I don't see anything wrong with it. As long as you are upfront that you are not ready to be emotionally involved and it's just friendly fun, that's cool. Hey, if it happens to turn into more, then it does. I have turned down a few offers from some very nice, good guys. The only reason is b/c the D is not final yet and I feel that it needs to be. As soon as that ink is dry, I'm free to do whatever I want and will not feel any guilt whatsoever.
"Success is the sum of small efforts, repeated day in and day out." Robert Collier
"One's best success often comes after their greatest disappointments." Henry Ward Beecher