Help! I led him on :(

I've been friends with this guy for ages and he started giving me more attention this summer. I was starting to think I could possibly like him, when he asked me out. He was super nervous and I said yes and told him I liked him back. I don't know why I did it when I wasn't sure of my feelings, but I wanted to put him at ease. It's now been a month and I'm pretty much positive I don't like him. The thing is, he is so sweet and thoughtful that I feel even more guilty about having led him on. He cares so much and I never let on that I didn't feel the way he does. How can I tell him I don't want to keep moving in the direction we're going, but that I think he's awesome? I wish I liked him but I just can't get myself to see him that way :(