she exhibits abusive behavior towards me from time to time plus other symptoms of BPD, i.e. Fear of abondonment, breaking up every other week over mundane matters.
This is hard stuff. How do you respond when she breaks up with you? What kinds of abusive behaviors are you coping with? How long have you two been together?
I agree with Notwendy, that the best way to support your GF is to see her efforts as good enough, even if they fall short for you (and even if you are 100 percent correct that she would recover better if treated for BPD).
She is brave to take a first step and to admit to herself and to you that she has a problem. Imagine a thousand pounds of shame burying her -- she is willing to start excavating the top layer. She has to start somewhere, and if she were to fully comprehend how thick and deep the layers were, she might not even start for fear of being overwhelmed.
Also, as counter-intuitive as it sounds, when you focus on taking care of yourself, it gives her space to self-reflect instead of constantly trying to protect herself from attention to her dysfunctional behaviors. You can model for her what it is like to feel worthy enough