Disconnect the buttons and guilt so she can push away and nothing happens.

Keep a log of some sort of what you do with/for the kids and make sure you yourself are happy with yourself in relation to your responsibilities and cares about them. You don't really owe much to your ex-wife and the more she pressures "reminds" you of how good it is to be out of there. So, try to be "happy" when she is being obnoxious :-) and even respond pleasantly as it will drive her crazy.