Matt, you keep trying to figure out crazy and I am thinking, after all this time, you should realize you can't.
MLCers do this with money. You need to get on it and fast. Do what you must to protect yourself.
And it really doesnt serve you well to continue to bash or assume it's her father. Whether it is or not, your path is still the same. Look after you and the kids.
Try not to go into the talk with the mindset that it is going to be awful.
Address the issues in a non-accusatory way, with control and steadiness.
