My girlfriend problem?

ok... i have been with her (val) for 3 1/2 years. we really love each other and she is my world. but she has this friend who really isn't the best influence on her. My gf makes her own decisions and all but this girl is drama. val has made some choices that effected our relationship. we have all known each other for 5 years maybe more. the three of us have been through a lot of **** over the last few years. to make a long story short one day her "best friend" calls me and tells me she has feelings for me. she also mentioned some things she wanted to do to me. i had no interest in this girl i'm in a perfect relationship. so i told her shes crazy and i would never cheat on val with any girl. the next day she calls val and flips the script saying i'm the one who called her. and the worse part is val believed her at first. after days of arguing some how i convinced her. so months go by and they don't talk. but now their friends again. i don't like them being friends am i for that?