I still like my ex and I can't get him out of my mind and I don't think I can handle being just friends which I think he just wants to be:( what should I do?

Talk to him, find out how he feels and tell him how you feel about him, you may win him back, The worst thing you can do is sit and expect him to make a move first, go I=and do it you have nothing to lose.
In the mean time don't mope about this, have some alone time with yourself, and ask "Do I REALLY want him?" what caused the break up in the first place? Ask these questions if you haven't already. Don't forget about the Graduation effect, which is throughout high school all we do is complain about it, but when we graduate we end up missing all those memories, Don't have those graduation goggles!