While it's true that you cannot make him do anything, it seems to me that he needs to be in therapy again...it is, if I understand correctly, the only way to control BPD.

Failing that, I think I would consider doing what he threatens you with when he loses control...call 911. I know from experience that can make someone who acts out like that rethink their behavior in the future.

Just because you love someone doesn't mean that you have to accept this kind of treatment.

DJ