My Ex: Can we still be friends?

Anyway, I'm having some problems with my best friend...who also happens to now be my ex boyfriend. We met several months ago and really hit it off becoming friends quickly because we shared a lot of the beliefs. However, it was totally platonic because we were both involved with other people at the time.

Before I knew it we were doing everything together: we'd go to church together, eat together, work out together, go to parties together, hang out at eachother's places and just watch TV...I knew that I could always go to him if I needed someone to talk to, and he was literally a shoulder to cry on a few times. He could always make me laugh and is generally just a lot of fun to be around. I couldn't keep away, he made me feel so good about myself and obviously respected and admired me by the way he treated me.

Well, when his girlfriend finally broke up with him, he says to me(a week after the break up): "Remember how we were talking about everything we want in a partner? Well, to me, you have all of those qualities and I was wondering if I could take you out on a date sometime?" I said yes, even though I knew it was soon, but he seemed confident that he was over his ex, and confessed that he had been harboring feelings for me for a long time. On the date he said he "saw where this is going" and wanted to be exclusive - again I was hesitant but agreed, because I really liked him at that point.

Fast forward two weeks: he tells me he feels like an idiot because I'm still the "perfect" girl, but that he just doesn't have feelings for me anymore and he wants to just be friends and be single. We agree to stay friends so everything goes back to "normal"...sort of. I've been giving him plenty of space...however,he still calls me regularly, almost every day and I see him almost as often (with other friends). I went for about 3 days without seeing him at all, but he still called me every one of those days, but it's not the same as it used to be. I don't feel like I can open up to him anymore. I feel like I've lost my best friend.

And now I'm at a complete loss. I still see him a lot but I don't know if it would be better for me to just stay away completely. He's indicated that he wants to get back together in the future but I don't think that I can take him back now seeing what he's becoming on his own. Before he seemed to be on the right track, but last weekend we all (him, me and a bunch of mutual friends) went to some friends' party at which he got totally drunk and flirted with tons of girls (even when I was around). I was hurt, but at least it made me realize that getting back together wasn't an option. Other than that he still treats me as a friend and I'd like to keep it that way except I don't want to give him the idea that I'm desperate or that I do want him back. Should I just quit the friendship cold turkey, or do you think we could ever really be friends again? Should I talk with him about it, or just let things be and see what happens? I am so confused right now and no one seems to have any advice, so please any insight is appreciated!