In your situation I would have been pissed off. As far as overreacting goes, well, that is part of the illness I think.
But just because one has BP, doesnt mean that every emotion we experience is a symptom. Yes, BP causes overreactions, and sometimes irrational anger, but there is also something called healthy anger.
Most people (at least women) I know would be really upset by that. So I would call it healthy anger.
Anger is a normal emotion, and it is healthy to let it out. It has to be room in a relationship for that.
I find that sometimes every emotion I have gets related to BP. But people who do not have BP can get royally pissed off as well...