Oh man I know

the first time the behaviors went off the charts when we were broken up. I just don’t know if I did the right thing reaching out tonight. Idk if it’s going to reinforce her silent treatment, and reinforce that what she did was right before that. But I did want her to feel that she could speak to me again without me being mean to her. I wanted her to feel safe to do so. I also wanted to take the lead and hold myself accountable for my moment of bad behavior. If I can’t, I can never expect her too
Fair enough, and I do think it's the right outlook.
From my personal experiences with my wife and oldest daughter (both BPD), the hardest part was to stop arguing over the past and live in the present. For instance, I was with my wife and younger non-BPD daughter a few days ago and my wife continued to make little shots....you never did this, you always did that. These were half-truths of her twisted perspective and it's so hard not to defend that stuff. For there to be a path forward though, that stuff has to die out.
One was, "You always said my work didn't matter, so I shouldn't have to contribute to the bills." Stuff like that is poison on a string...don't pull the string!
Just remember that in the face of that stuff, use affirming statements to move past it. The past is set in stone and there's no good from reliving it. "I'm sorry, I wish that could have played out differently. Can you forgive me?" You side-step that stuff and seek closure to focus on the present.
Again, I wish you luck...hopefully she responds.