Need an opinion and a quote please?

Okay so me and this Senior(i'm a freshman) really liked each other. He asked me to ask my mom if we could date and she said no because hes too old. I have not been able to stop thinking about him in like 2 months and its driving me crazy. Just recently we started talking again and i like it. Well my friend crazy flirts with him and she doesn't know it. Then at the basketball game we all hung out and she put her head on his shoulder and he said "I'm nervous." He told me he didn't get nervous. Now she told him she likes him and he told her he likes her. Well i know she didn't like him when i was seeing him because she was seeing someone else. But now i think they are gonna date and it kills me. She knows it and she said shes sorry she can't help it. I don't wanna be jealous or anything but i am. and i can't stand to see them together because it makes me go to the bathroom and cry. Am i in the wrong here? and are there any quotes that would go with this or songs? like backstabbing or betrayal or something... p.s.- sorry its so long.