wat do u do when ur bestfriend falls in love w/ u?

IM A GIRL, MUH BEST FRIEND (A GIRL) TOLD ME SHE WAS IN LOVE WITH ME....IM STILL YOUNG TO KNOW, BUT IM PRETTY SURE IM STRAIGHTER THAN.....A STRAIGHT LINE?? (BAD SIMILIE, I KNOW....) SHE IS, WELL, CRAZY. INSAINLY IN LOVE.....IVE TRIED EVERYTHING, SHE JUST WONT LET IT GO....ANY SUGGESTIONS???