What is this that I'm feeling?

Hello~~ I've been feeling really bothered lately as I'm confused by what I'm feeling about this guy which is my good friend. I'm good friends with this guy whom is 2 years younger than me. He is a social butterfly, he has lots of close female friends. Meanwhile, I'm a little more conserved towards people I'm not close with and I've got only a few close male friends. I'm the oldest in this clique that I'm with this guy friend, and I think that's the reason why most of them look for me first if there's something bothering them. The reason why I'm feeling confused is because I'm pretty positive that I won't fall for guys who is younger than me. I've always been against guys who is younger than me. And this guy friend, he's always teasing me and calling me names like fat, ugly and stupid. I don't get offended though, I'm pretty used to it so I call him names too. But sometimes, he often caught me off guard by praising me indirectly. Saying things like "you're cute, your face is so small (while comparing his hand to my face), your legs is pretty long". We often bicker, so it's really rare to hear him saying nice things about me when most of the time he calls me fat and ugly :/
although we rarely talk when we don't meet, we don't text or call each other often. But I see him almost 4 times a week when we have class together.
I've been dreaming of him, sometimes daydreaming about how we'll bicker when we meet... I'm pretty sure I don't like him though... but I'm really confused by what I'm feeling...