My best friend and I just graduated high school, and Ive had a crush on her for five years. How do i tell her?

I want to tell her before we go off to different colleges (which are in the same city). I'm not looking to hook up with her, and I'm not even aiming to get her to be my girlfriend, although that would be an awesome bonus. I just want her to know, cause i feel like if i don't tell her before summer's over, I may never get the chance again and i would beat myself up about that for the rest of my life. She and I know each other better than anybody on the planet, and i don't want to screw up our friendship over this. Any advice?