I think you need to do something. You seem stuck in a paralyzed mode watching this stuff happening and feeling powerless to do anything about it.
I would prefer to see you hire a competent attorney who will advocate for you but not turn this into WWIII. Swift, decisive action is always a good thing. I'd like to see you hit him with the support and custody case with no advance warning. He is sitting there feeling as though he has all the cards. The strolling in the house every night is ridiculous. I would seek a kick out order as part of the support and custody case.
If you can't bring yourself to do that or don't think you can pay for it, then I would send the letter. If he didn't respond or didn't respond appropriately, I would then file the case without any mention of it to him.
I think 25's situation is different from yours. I think if I were to file for divorce, I would be in 25's situation but I think there is a lot of narcissism with both of our H's that I haven't seen with yours.
Yours seems more like a petulant child to me, less menacing. I think standing up to him as Train has suggested again and again would knock him for a loop.
I haven't yet heard back from my friend, but I checked on some profiles for folks in your area. Elaine Silver is one I would definitely call. She has the right board certifications, she only does family law, she can help with collaborative divorce if it comes to that, she seems to focus on resolving disputes.
