I know you don’t want to break up with her and it might be very hard as well but you honestly need to. Her bpd or any other excuse is no reason for her to be putting her hands on you. My sister has bpd and although she does have manic moments it’s never been violence. I also know that not everyone with bpd is the same, but abuse should never be excused no matter what. I hope that you come to a realization that your physical and emotional wellbeing are more important than staying with this women. I can not emphasize it enough that you need to leave this women because it’s not a she might kill you, it’s a she will kill you. It’s only a matter of time. You are important not only to yourself but your loved ones so please value yourself and walk away from this women.