Boy problems?

okay this girl in my homeroom cl became my best friend really fast before that a guy named christian use to be my best friend and now she likes him and even thought i like him too i am trying to get them to go out. (i don't want them to thought) so the other day was our school formal and i told him that she likes him and well since she is my best friend i thougth that i will help her out and i told her to get one slow dance with her so he did. (oh he has a lot of girls after him) so at last he asked me to dance after he was done with her i couldn't say yes because my best friend would be hurt so i turned him down i called him and explained why i said no and everything but i feel horrible i really like him. Now me and him made this thing where we consider each other as bro and sis so he calls me his sister and takes care of me as a sis oh and my best friend is going to move in 2 months so i thought i will give her the best time of her life in the 2 months left but it kills me inside