What could I do?

Ok, this kid has being my brother's friend for a few years now. He is at least 6 years younger than me. I didn't like him at all cuz I felt he took my brother away from me cuz I didn't have friends, just my bro. Now ,he came to work were we work and I started "knowing him better" and end up thinking he was a good person, kind of immature, but well, he is a kid. After a couple of months he moved and we continue talking, but now he says that he likes me. I felt that he liked me before, but since he is so young I didn't want to say anything. I end up caring, almost liking him I guess, now that I know that. He barely says something besides "I like you", "I miss you" and so on... like all the other guys I've being with. He also said he didn't have a gf but there was a girl talking to him like she was his gf on fb. Now, after he said that an started posting things like "she got me confused", "she'll be mine", and other phrases, (which I stupidly thought were about me), I saw he has a new gf, a girl different from the other one. So, not only is he a player, but he is also a nice kid that I end up caring about.
Thing is, I want to make him feel bad for what he's doing somehow, or more like make him understand that what he is doing is wrong. He is too young and I think he actually has good intentions in life, he is very smart and he shouldn't be a player. I don't know, maybe I should just forget about him, completely and just continue looking for The Guy that's for me.
Anyway, thanks to anyone that would care enough to even read the whole thing.
I'm 22 by the way. And I've told him I want to only be his friend cuz he is too young and also cuz I believe in friendship before anything else... he said he wants to be more than my friend.
-_- Sometimes I hate having a heart...

you most tolk to him sense you older ,you the one who most to let him understend that's he's a player ,and maybe you wrong ,maybe you understend this boy wrong you most have a conversation with him first to now this .