Sweetie, you said, "Do I have to be in control of how it ends? My gut tells me if I just back off, it will end even sooner."
You may think you are backing off, but you aren't.
You really need to stop talking about her, referencing her, asking about her, at all.
Now, if he is texting again, restate the boundary the way Mach suggests. Then say nothing. Happens again, decide what you want to do for you.
Then, back off for real.
You know we all care about you, this is why we are trying to drive this point home.
Listen, this ow stuff is hard. It ain't for the faint of heart. I know you just want her to move already and be done with her. But, she is not the problem, she is a symptom of whatever is going on with your h.
That is why you have to let him do this in his own time. You have to let him figure it out himself. Or you could keep doing what you are doing and get dizzy. Your choice.