I'm so confused!!!

I honestly don't know if I'm in love with my best friend or not. I'm a gay girl, but she's straight, so I know nothing's gonna happen. Thing is, I'm not really physically sexually attracted to her, though she's really pretty. However, emotionally speaking, I love her so completely that I can't even put it into words. I mean, I would literally jump in front of a train for her without a second thought. I really have no other true friends than her, so I don't really have any other friendly emotional bonds to compare this to. Am I in love? Help me... Is it normal to feel like this?