Friend with benefit dilemma......?

I think I messed up. Ok details. I'm 24 and have been friends with this guy for almost 7 years now. We are both unattached people who agreed in the beginning of this thing that this is just a friend with benefits thing. Well its been probably about a month now and he's wonderful. We go out to eat, hang out, basically friend type stuff. He doesn't ever let me pay for anything though and occasionally talks about stuff we'll do in the future like go on trips and stuff. The past couple days I've fallen asleep over at his place. The first day, I left while he was asleep because I had a few things I had to go do myself. About an hour after I left, he called upset because I didn't wake him up before I left (nevermind the fact that I would be coming back in just a few hours.) I know he texts other girls and he has other girls who are always trying to hit on him. He's a very attractive guy. My problem is...I kinda realized tonight, after he sung the country song "Good Morning Beautiful" to me, that I'm growing attached to him. I mean I care about him as a friend, always have, but this is different growing attached. What do I do? Do I call off the FWB thing or just back off some? Do I tell him what I'm feeling and possibly lose all of it? Or just sit back and let whatever happen? Pretty sure I messed up.