I have a sort of dillemma, need a few wise words?

I am 15 years old, and I live in Mexico. There's this girl who lives in California, which I know because she's the granddaughter of my former principal. Now, I think she is beautiful, but I haven't told her anything because she has a boyfriend. She's moving into my city to graduate with all her mexican friends, and she's going to break up with her boyfriend. Now I wouldn't be too quick to go out with her in the first place, but still, I don't want to be just another boyfriend to her. I don't wanna risk losing her, but I hate seeing her with other guys. Should I wait until we're adults and I've finished my education? so maybe it could be more serious, because I'm never going to meet a girl like her, and I know it. Right now we're best friends, and I want to be more, but if I go out with her now, I could risk eventually breaking up with her...