Advice on breaking up with long distance boyfriend? :(?

I know this sounds pathetic but I've been really confused lately. I have been in a long distance relationship for almost 6 months now. I am 15 living in new york and he is 17 living in California. I know we're young but i have fallen in love with him. Since we never see each other, I've been pretty depressed. I cant keep going through the heartache and need some advice on how to end it so its not too big of a surprise to him.