He doesn't want to sign it because he's most comfortable with the limbo status he has with you. He can be nice and be "family" Dan when HE wants to and you and your kids are there for him. When HE wants to be "single" Dan he can be that as well contacting the OW or being simply by himself, knowing that his other option (you) is just one of his mood swings away. As long as he can keep this going he will. It is a control thing with him. If he signs the paper and you move on, he loses not only the "family Dan" option, but you as well. He's used to dangling you on a string. I agree with the others here, you need to take control of the situation.
