Bee-eff-eff question/problem?

Mmk. I kinda told my friend that I like her boyfriend. ( and I liked her boyfriend way before they even went out.) So at lunch today [ at school ] I waved at him.. and Kandi [ my friend ] got mad at me.. and wont talk to me. Just because I waved at him. And I went all *****-mode on her. Yelling. And cussing, but I didnt care.. because she had no right to act that way towards me. Then one of my other friends told me that Kandi was in the halls saying how much she hated me and wanted to '' beat my *** '' So all of this happened because I liked a boy who she's dating.. After I've like him longer than she has. I just dont get it.. Help. :(