I'll give the advice that is given to me and I hate hearing... But it's true. You can't control his actions!
If he files for D, you will then have your answer, like it or not. Terrible to hear. In the mean time, as long as YOU are stable, don't worry about it. When the time comes, deal with the D. If you want to stall, you can stall for years. He may or may not stop part way through, you don't know. Make it uncomfortable for him now as if you are already D so he can see what it is like.
My W made it impossible for me to live on my own, which forced me to file to protect myself.
