Two crazy girls...one me

I think my daughters are bipolar.

That's probably not true...and I know it doesn't sound very nice, but they are so up and down that it scares me. I don't have sisters, so I know nothing about their relationship. Seems to me, like these girls are a little off their rockers. They are BFF's and play wonderfully for like 20 minuets. Then all of a sudden they turn into little she-beasts ready to rip each other apart. My husband and I are jumping over furniture and peeling hair out of hands to get them away from each other.

This can't be normal. Then someone had the nerve to tell me that it gets worse as they get older........so they are going to murder one another at some point then?