How do I tell the girl I like she acts kind of bipolar?

I'm a 13 year old biual. I like my friend and she's bicurious. She says she might be startin to like me a little bit. Which is great but there's a problem. She's a little bipolar. One minute we'll be laughing and flirting then she starts acting like a b****. She says a bunch of mean thinks to me and it kinda hurts my feelings. Then later she says a bunch of nice things to take back what she said before but it still hurts. I'm not sure how I should handel this. To her and everyone else at my school I'm tough but I'm really sensitive and when she says all those things she really means it. Im not sure i can deal with it anymore. If i tell her im sensitive and she hurts my feelings i'll sound like a wuss. And she might stop liking me if i tell her it hurts me but i really like her and dont wanna get over her or make her stop liking me. What do I do?????