What makes BPD different from any other personality disorder is that your anger and impulsiveness -- acting out, kicking over a chair -- only happens when you're dealing with people you really love. If it's somebody you don't care about, who cares?
The disorder got in my mind and said, you know, things like 'If she hangs up the phone one more time, I'm going to break something,' ... and so, to me, it all seemed perfectly logical.