I agree with Marie123.

You could also go to the source directly: ask her why she does it. We could speculate to the moon, here. If it is a BPD trait like her fear of being abandoned by you, that must be hard for her. How painful to feel and worry that people you love may just up and leave (and I'm not condoning her behavior, its disruptive and need to change, hopefully she is in therapy and getting help). As her mother, have you gotten any support or counseling yourself on how to interact with her with her new diagnosis? Maybe you could reassure her that you won't abandon her. But first, you have to find out - from her - what's going on with her. I also suggest cultivating compassion. Annoyance and callousness won't likely get you far with her, whether you care about your relationship with her or you don't. That doesn't mean you compromise your own boundaries or be a doormat. And you're certainly allowed to feel annoyed by this, as that's a natural reaction too, and I don't know what your relationship is like with her. I just noticed a lot of negative talk about her from you.