Im gay and my best friend (a girl) has been convinced by her boyfriend that I'm in love with her?

Hopefully you do not live with her so can't you just be very busy for a while and distance yourself. People who do not listen are selfish. Im sure there are others out there who would love to have you as a friend and wouldnt sabotage you like that. Can you let your phone take messages for a while and be unavailable?