Shes mean to me about him, friends and crushes Options

[*morethanfriends...]

So my friend (I told her I liked this guy named Craig) just sudenly started flirting with him...and I donno how to act. He likes her and she said he likes him just a little. But she never really talked to him really before...I donno she supposally says they were friends. ButI got in a fight with her about that. I told her that it hurts my feelings. She seriously now goes up in front of my face and hugs him and leans on his legs on the bleachers and touches his chest. She flirts CONSTANTLY, and turns to see if I'm looking sometimes. I HATE it. She said it might matter to me but not to her (so she doesn't care). And since we're not going out I can't tell her to do anything. I wasn't telling her to do NOTHING...just to maybe not do it in front of my face. I wrote that in a note and after she read it she threw it back at me. She says she doesn't like him now so why should it matter. She's in every single one of my classes except music and band. (So math, science, social studies, language arts, and lunch because I let her sit at my tab;e because she got icked out of 3 and had no where to sit). I'm ready to kick her out. I'm her only friend left. Should I be mad and let her go? Please reply, I'd really appreciate it!