How to deal with a clingy and needy friend (Please read)?

I have a friend who is a guy and I've known him since 6th grade. We've never been close up until my sophomore year. We kinda drifted apart my junior and senior year but the summer before my freshman year in college we began to talk again. All throughout our years in school, he's liked me on/off and has asked me to be his girlfriend which I said no because I just didn't feel that way about him. Anyways, during my first semester as a freshmen, we became good friends again and started hanging out a lot more because he goes to the same school as I do and was even in one of my classes at the time. He started liking me again and asked me out again but like the first time I just had to say no because, honestly, I can't think of him anymore than just a friend. I don't want to come off as snobby or "too good" for anybody but I'm just NOT attracted to him whatsoever. He's a very nice guy and not a jerk at all but it's actually his "niceness" that's bothering me. Don't get me wrong! I don't like jerks and I appreciate his kindness but he has been WAY too clingy and needy and I don't think I can handle it anymore.

For example, something went wrong with my Facebook, apparently, it had blocked him for a couple minutes and I had no idea. He texts me asking my WHY he can't see my page and if I blocked him and so forth in a rather demanding way. I told him that I didn't block him but that maybe it was Facebook's fault? He then texted me back saying that he texted our other friends to see if they could see my page and that they could....this is what set me off. I couldn't believe it, it's like he's stalking me! One time I accidentally left my phone in my car one time while I was in class and when I checked it, it had 7 missed texts from him asking me why I was ignoring him! I got so annoyed.

He's ALWAYS wanting to hang out like 24/7 as if I didn't have a life. When I tell him that I can't he tries to make me feel bad or he gets all emotional and honestly, as I'm typing this, it sounds like I'm talking about two people in a relationship. I've told him countless of times before that I like him as a FRIEND and that by going out with him as his girlfriend I would only be lying to him. I've said it in the nicest way possible and he says he gets it but apparently he doesn't.

I guess what I'm trying to ask is what can I possibly say to him and how can I approach him? It's hard because we have a lot in common and he IS my friend after all, I would even say he's my best guy friend, but he's starting to treat me like a girlfriend....I've tried to stay friends with him for sake of our friendship but I don't know what to do. He's completely insecure and emotional and his neediness is weighing me down. Please any advice?