It is hard to be bipolar (I'm a BP II) and to have mood swings but everyone needs to learn boundaries for their behavior and that they can't mistreat people. If she isn't in therapy I'd recommend she start so she can learn some coping skills for calming herself when she gets very angry or agitated. I know when I get very upset at my husband sometimes I can't calm down for awhile and so I've learned to take a "timeout". It really is important to develop coping skills because she will have lots of situations in life where people trigger her and she cannot explode inappropriately without consequences. You can be loving AND firm and though she may hate it now she will thank you later.