HELP! IDK WHAT TO DO! GUY PROBLEM.?

I really like this guy, and heres our little story together:

About a year and a half ago he asked me out, but I didn't like him back then so I rejected him nicely, and he kept on liking me, and so then in december I told him that I liked him, and then a week later he got a girlfriend. (I swear on my life he only did it to make me jealous.) but then she broke up with him and left him for his cousin. Then in the hallways he'd always stare at me, or make eye contact with me and never break it until I did.

Then this Summer a couple of weeks ago I saw him at my physical and I sat about 3 rows in front of him at the doctors office. (This is actually the second year in a row we've had physicals same day, same time.) Then a few days later he messages me on facebook and we talk for about an hour and in that hour we sorta just talked and talked. He always used smiley faces like this:) in every sentence basically. He asked me for my number. Then he texted me afterwards for a little bit but then randomly stopped responding.

Now I am here going crazy. I think about him everyday, when I listen to songs they always remind me of him, whenever I watch a movie I always think of him, I just can't stop thinking about him.

Then today at church his brother and him sat right behind me and my cousin even though there wss four empty pews in front of us, and my cousin would always look back at him and he'd be looking at me, and one time he had a smirk on his face.

What should I do?

I don't know what to do, it's killing me.