Personally, I would start itemizing everything and making him pay his share. It can be seen as nitpicking, but really it is just making sure everyone is paying what they should. They are his kids, too, and just because he wanted out of the marriage doesn't mean he doesn't get out of paying for his kids like the court ordered. These are the consequences. Let him feel them, he needs to, and the kids need the money and a mom that is not completely broke because of it. If you don't, one or both of you will end up holding resentment because of those little things you just cover that add up.
