Hi silentangel, are there then some things you can have him help you with?? And have a plan in place for if he doesn't come through for you?? Perhaps if you set some real clear things you can agree he can do/be trusted to do and then maybe build on them if he can be trusted/if he comes through??
But as for your children...........if there's any help he can give with them even financial or practical which makes things easier for you, then I wouldn't call it "helping", I'd call it his responsibility,
And while it can be important to move on from the past sometimes, is there a real understanding from him about what went wrong in the past, why things went wrong, and any ways you're both using to stop it happening again??
But you mentioned counseling, by the sounds of it some of the issues have been his?? Do you think he'd agree to go along to couples counseling with you?? Even if you're not "together" you're still in a relationship of a kind while you're living together.
And if you're thinking about the consequences being real big if things fall through, maybe you could make it a condition that he goes to counseling with you if you're going to "take a chance" on him??

Alison