It just never worked when I begged her to stop.

I feel you.. I begged my expwBPD to stop with silent treatments, and if she couldn't do that, at least talk to me at times instead of forbidding me to communicate or message her all together. She told me to stay away, not contact her, and leave her completely alone. Sometimes for weeks. She has no idea how much that has impacted me.. and if I tried to tell her how much she was hurting me or hoped that we would sort it out all I got back was "Well, I am hurting too", "Well, look at me, you think I'm doing this for fun?" or something related. Obviously I knew she didn't but at the same time she shouldn't be in a relationship if she can't regulate her emotions.

In the end, me asking for help and me asking her to help us is what got me discarded. To her it was strictly forbidden to contact her during silent treatments but I kept pushing because it hurt and she wouldn't understand. Obviously, I am happy to be out, but like you, a part of me wishes we could have worked on it all.