I would like to bring the topic up to her, but fear she would never want to talk to me again
I did tell my gf I knew about BPD and she related to most symptoms when I told her, but she never acknowledged she had it though I'm sure she knew before and played dumb.
What exactly do you wish to happen from her telling you she has BPD?
Maybe she doesn't know she has it, or can't put a name on it even if she has the symptoms, maybe she knows and will play forgetful like my gf.
I also get the feeling she is very promiscuous. But I love her, and am still so attracted to her.
If you're willing to put up with her promiscuity then play the game, friend with benefits or whatever you and her agree to; she seems more comfortable with some emotional distance (best friend vs date).
If not you need to do some serious soul searching about why you want in on a relationship you know you have an issue with (as in, you want exclusivity while you know she can't manage it)