Good that you are going to a therapist. Do you know if the therapist is aware of DB or is M friendly? Yes, keep us posted on the sessions, especially as it relates to the two of you.
How long to give your H is entirely up to you. What you will specifically be looking for is that your H indicates that he wants to work on the M.
Now let's not put the cart before the horse. IF your H indicates and shows he is working on the M, THEN you may want to ask if OW is no longer in the picture. But...
That is up to you. AND... the proof might be him being transparent about where he is going, who he talks to, etc.
But like I said, looking or asking for proof or transparency is way too early, at this point.
If you are going the route of focusing on personal improvement, than the OW is a moot point. Be friendly, but keep it as such. If he wants more than friends, then you may ask him to commit and ask for time to see that he IS committed. You may want to decide what commitment looks like, to you, so you can let him know, if it comes up.
Let him engage you. You do not have to be no-contact. Just keep yourself available, but distant. He takes a step towards you, you allow for a moment, then back up a touch. Make sense? It might make him desire you more. Being unavailable may make him think that you are holding a grudge and will not forgive him if he DOES want back.
Do you have any guesses WHY your H might want you to call? Does it seem like small talk or does he appear to want to know your where abouts at any given time? If it's the former, great. If it's the later, then you want to be mysterious about your comings and goings.
He has to commit before he gets to know everything you are doing at any given time. And even then, that's a bit controlling of him.
