What should i do about this girl?

ok, i found that this girl that i sit next to in 4th period has a crush on me, shes 15 and im 16, i was a little surprised that she has a crush on me but she has a boyfriend, i dont like the fact that shes not single and she has a crush on me but i have no intention of breaking her and her bf apart so she can come to me, i dont really plan that to happen, im a little confused of what to do, abd i cant talk to her about it because i wasnt suppose to know, its her little secret but my friend found out about it and he told me, i like another girl but im getting over her since she made things awkward and when i started talking to the girl who has a crush on me i began to like her before i even knew she liked me. i dont know what to do so give me your opinion on this