Its only 3m, I’d not worry about anything like exes at this point
Wait till 6m and then see what he’s like.
Why does he have to “tell her”? It’s not like she has any say in his life anymore, so perhaps at 6m he’ll be more sure about his relationship with you and then perhaps it’ll just get mentioned or come to light
If he’s otherwise ok, let him know that you are a little worried that he seems to make a lot of time for an ex, but that as it doesn’t impact you Directly so far, it’s a benefit of the doubt situation for now, but that you won’t be in the shadows indefinitely and that he does need to focus where he wants to move ahead to, not walk away from.
He my be feeling guilty about moving on, they were together a long time, and tbh it sounds like she’s highly manipulative with the self harm threats/fears.
Again, raise this in a couple of months and make sure he knows that you’re not likely to put up with her calling the shots in your relationship
I had this kinda with my oh, his exw is highly manipulative, she tried all sorts of shenanigans with their daughter when she got wind that he’d found someone, but it backfired on her completely and now a year or so on, she’s under no misapprehension of where the land lies.