I had the same type of relationship my senior year of high school as well. And when the time came it did hurt but there is so much life and so many people out there for you to meet. My ex and I are still friends now, but it didn't happen over night. My advice to you is to enjoy the time you have and maybe you'll make a long distance work. But it's incredibly tough so don't get discouraged if it doesn't work out.
Just remember you both care about each other and when you cross paths to not become bitter if things don't work out. He'll still be one of your closest friends, and if the time works out again you may get that chance to make it a committed long term relationship.
The advice I wish I was given at your age was to be excited about what comes next. After high school you're going to get the chance to find out what it's really like to be you so enjoy it and make friends instead of waiting for things to go back the way they were.
And finally don't discredit anyone you've met in high school because people change drastically. Some people you never liked in high school may become close friends, and others that you were crazy about will fade in the background. For now enjoy your relationship and when the time comes know that if it has to end you'll survive and if it's meant to be you'll make it thru even if you have to take a few breaks along the way.
Good Luck!
Ted, how do I explain this to you. Last night, I ate the best cake of my life. Do you think I'm gonna let that cake out of my life? Hell no. I'm gonna find out what bakery made that cake and I'm gonna get some more cake.