Should I tell her

My best friend has a crush on this guy for two years. He leads her on during the school year. But ever since she started texting him he never has andwered, and I'm sure he has his phone. Recently I was told by a close friend of his and mine that he has a crush on two other girls in our grade. I'm debating whether or not to tell her. Cause all the signs point that he doesn't like her . She took all advanced classes just to have a chance to be in the same classes! Should I wait tell the beginning of the school year or tell her sooner then later ? If I told her I feel like she would be crushed emotionally. I don't know what to do . I can either be loyal to our friendship or try to keep her from being devastated.