How do i deal with someone who is lying about me and likes the same guy as me???

A girl that i know likes the same guy as me only because she knows i like him and he or his brother don't even like her as a friend but she doen't know that and she is saying that i am talking behind her back when i'm not even at home and haven't talked to my friends alot or anything so plz help out i realy need it plus iwant to tell her that the guys don']t like her but i don't want to hurt her feelings all though i hate her guts!!!!