Oh crap. Please please help!?

You're going to need to step back a bit. All the heavy flirting needs to stop so that he doesn't continue to get the impression that something could happen between you two. If you have drop the 'You're such a great friend.' line to him, then do it. Let him know that you don't think of him that way without actually saying 'I don't want to date you.' It's a sticky situation that I've been in myself, and I'm not good at being upfront about things too.