While we can certainly contribute to the dysregilation of a person with BPD, the extreme bahaviors and acting out are more about their dysfunctional coping mechanisms. She may be used to volitility, and when you went no contact to distance yourself, it triggered her anadonment fears. Telling you to go kill yourself (in effect), is uncalled for, certainly. You did what she asked, but it triggered her anyway.
Healthy seperations usually have a mutual agreement, with the break or space defined, even loosely, like, "ok, I'll text you in a week to talk," or something similar. But that's not what happened. Like
shatra said, she's likely split you (
see here for more on splitting).
Is this what you're strugglng with the most, closure?
What would closure look like to you?