How do you help a friend who is in love with someone they met on xbox?

My friend is a great person. She is very beautiful, creative, and intelligent. Unfortunately someone is taking advantage of her. She is in a very vulnerable state. This guy from the U.S (she lives in Canada) met my friend online from xbox. They met on the game Halo. He has basically told her she is beautiful and he loves her and cannot wait to be with her. She is now “secretely” dating because she doesn’t want anyone at school to know and think she is dating a creeper. She gets into little petty fights with him constantly and it makes her so sad. He will make her feel bad for things that really shouldn’t matter. Everytime she talks to another guy on xbox he gets jealous and ignores her and if she does not say goodbye to him he ignores her and says things like “It is ok hun, if I was talking to someone else I would stop and make sure I sad bye to you because I love you so much, but don’t worry about it, it’s ok.”. How do I get rid of this creep in her life without offending her or losing her as my best friend. I love her so much and I know this guy is just taking advantage of her. She has already had a past with a creep taking advantage of her as little girl. He is planning to come to Canada to visit her this summer! Please give me any advice! I don’t want another sick freak to hurt her, she deserves better.