I guess it's over

[Dom R]

I do NOT want a D. But if I am going to move on, I will need to get one.

Some people jump from "tenaciously hanging on", right into divorce.
I personally think that is a mistake, and the better thing for everyone involved, is to fire a crystal clear "warning shot" first.

A plan B letter, can do that well, if you decide to head in that direction. Particularly if you are explicit about,
"This is what it takes to be with me. I will wait for a short time for you to make up your mind. but i will NOT wait for long".