Fence sitting [censored] and it will eat your soul. Want to stop all that nonsense? YOU file for D. It doesn't mean you two will go all the way through with it but it will force a "come to Jesus" moment where you're either going one way or the other. Right now he's a cake eater. He has a family and probably OW. Both whenever he wants them on his terms. No no no. You can't allow that. You have worth. You won't put up with that crap. He's back and forth as you say. That's no way to live. You're worth too much to put up with that. File for D. Shock the paradigm.
