Help me forget? Please?

Every time I've parted with a girl I've been able to easily forget, whether it was a break up or one of us had to move. But this time is different, I met this girl at a week long NASA scholars camp, and we became pretty good friends. I really like her, but she lives out of state, I got her Facebook and her number, and we've been keeping in touch, but it just isn't good enough. I'm 17 and I've never had to deal with this kind of sadness, can someone help me please? I feel like crying, I've never felt like crying.