Really get this (of course, having a borderline personality, I'm not sure, but I believe it, having BP, actually schizomania): a borderline personality is a extremely powerful defence mechanism, extremely powerful, and it can be extremely destructive for some people, still far more so than it is for you. I strongly believe it can literally make someone schizophrenic, if they have a/the vulnerability, but it can "kill" people with severe depression.

I traumatised (our BP mother didn't help) my sister severely. Luckily, she doesn't have much of a vulnerability for severe depression, but she's nevertheless in therapy.

Just out of curiosity, but it may help with assessing what's "wrong" with your boyfriend, do you have any siblings? Do they, or does he/she, act similarly to your boyfriend?