If he agreed/claims that he has cut off contact, you can reasonably want some transparency. One problem in the near term is that even if he really means it, he will probably slip up. So, you have to ask yourself if you want to know about that, as things stand now. I think it would be fair to tell him that you are going to be checking, and asking him for information (to see his phone, bills, whatever might help) from time to time. I don't know that it is time to draw a line in the sand, yet, but I think letting him know that you are watching is a good plan.
In the meantime, make sure you keep on taking care of you! That's where the real progress comes.
