Silent treatment is a form of abuse. It’s good that you aren’t groveling in that you are not responding in the way she had hoped—you aren’t accepting your *punishment*. There’s not much you can do about this, other than what you are presently doing—so keep up the good work and do something enjoyable. Some members here report that they’ve actually learned to enjoy the silent treatment as it is a break from constant bickering and it gives them time to do fun things.
Take a look at the Tools section above to learn strategies to dial down the temperature before she turns to her strategy of blocking you out by not talking.
As far as therapy—it’s a challenge at best to get people with BPD into therapy and have them continue when it gets difficult. BPD is a shame based disorder and people who have it are reluctant to do a deep dive into self examination and behavioral change. Here’s an article that helps explain the issue:
https://bpdfamily.com/content/how-to-get-borderline-into-therapy
