I would agree, because I'm about 99% sure my girlfriend is bipolar.
How should I handle this?
Ignoring her while she's upset will feel the equivalent of her feelings being invalidated or unimportant to you. Let her know that you are there for her if she needs to cry or wants to talk calmly, but don't play in to arguments or screaming matches. If she starts with something like that say something to the effect of "Babe, I love you and I am always here for you. I know that you're going through a difficult time right now. Let me know when you are ready to talk." Confirm that you are understanding the issue she is having by asking directly, "So what I'm hearing you say is..." And no matter what happens, try not to raise your voice. Remember also that she is allowed to be upset, but that it's not an excuse to take advantage of or abuse you. Do not tolerate that.