Would this be a good idea considering the situation I'm in?

Yea use facebook. And don't say "hey I have to talk to you about something," just say "hey." Then she'll respond and just have a normal conversation with her. No need to jump and immediately tell her what you feel, take your time. Just start talking to her on facebook and tell her eventually. You can make it evident in the way you speak to her, but don't make yourself sound like a douchebag.