I would add that since he has been threatening to leave anyway and has been staying in motels, I would be relieved if he was to leave. What a bunch of manipulative quacking. How stressful for you. Don't let the door hit ya on the way out, dude.
My ex pulled that disappearing act. He'd go out and just stay gone for days. I still wonder if it was to spend time with someone else, but I'll never know. Regardless, when I asked him to move out he went. A part of me was upset that he didn't try to fight for us at all, but I was still relieved that he was gone. He was free to run his life into the ground and I didn't have to deal with him.
I hope you will get to the place where you see this is a blessing instead of a tragedy. You can't stop his self-destruction but as they say, "Let go or be dragged."