Bipolar is absolutely no excuse for that kind of emotional abuse. My fiance has BP 1 and I have BP 2 and neither of us have ever been abusive towards each other, even at our very worst. Sure, we (especially me) get irritable and snap at each other. I do on very rare occasions get some of the bipolar rage issues, but even then there are limits, because I'm basically a good person and not an abuser.

No mental illness is an excuse for abuse. Period.