Aside from the best friend issue...
I went into college my 1st year with a girlfriend still in high school. Long distance relationships are VERY DIFFICULT. If you don't think that you two are BOTH mature enough to handle it, then recommend being friends and if things work out in the future they were meant to be.
However, stop lying to him and telling him that you're not ready. Also, if he's so sweet, has a great personality, and will do anything for you...isn't that what all girls want? It's not always about the outer appearance and physical attractiveness. It's what's on the inside that counts, right? If you care about someone let them know and don't lie to yourself about it!
Need Help on my Question! link