Self defeating attitude I think is what you are after there.
Next time he says soemthing negative like "It won't work"
try
Giving up on your famly so quickly? Without even going? You must be a very proud father.
Children are damaged goods after a divorce. Even an idiot knows that. And you want to RUN there?
Your kids will be very proud of you ... Dad.
OR
Won't work? Of course it might not work. But skulking around facebook for old girlfriends isn't going to help your kids have a stronger famly now is it?