I would say that if he comes to you again with it, tell him there are certain things that will have to be done and there are boundaries that will have to be put in place. Then lay it out there. Definitely he should not be the one to decide how it should go. We know what his idea might be. He should have input; I didn't mean it like that, but he doesn't yet know what he really wants.
I really agree with your "not now". You need time to heal from his betrayal, and to live for yourself. vc
