"it was too difficult for her to talk about & just went quiet."

Then you should have asked her why.

You keep mentioning an "ultimatum". No one said you had to do that. Establishing a boundary is different.

"The only thing that MIGHT change this is if I filed or moved out, "

No. Those aren't the only options.

Obviously there's something still bugging her. What is it? Have you asked her what is it she wants?

M-43 W-40
2D - 9 and 5

Emotion, yet peace.
Ignorance, yet knowledge.
Passion, yet serenity.
Chaos, yet harmony.
Death, yet a new life.

RECONCILED AND WISER