Gone crazy for this girl?

She dam pretty, smart, popular, nicest personality, but she has bf, but they been together for long time!!!, (im 15) i asked my friend to ask her what she thinks of me, she said im wired but very adorable, funny, nice and sweet, we stare at each other when p in the corridors, the look she gives me is out of this world, i tired to talk to her, but i cant her looks intimidates me, she the sweetest girl i ever seen, i think about all day, then week ago she broke up her bf, he was cheating on her,( cant believe he would do that to her, she had 4 year relationship with him) i have number on mxit, i was thinking to leave message about what think of her and my sympathy towards her, then come back later online and see how she respond, she walks past were me and my friends hang out, flirts with older guys, and stares at me constantly when she does this, what should i do, but sometimes I feel like should start any between us cuz im leaving in 3months, but i love her and never seen anyone like her.