Well you already made the most important step: recognizing he's no good for you. It can be hard to turn away from things once you're attached. It may be hard, but you need to consider what would really go down if you two were to get into a relationship. Would he still be nice? Would he still care? Would he treat you with any respect or kindess? Honestly, the answer is probably not. Boys like that often go after girls simply for the chase. Once they get them, they lose interest. I've seen and heard it happen. It doesn't hurt him any either, you're the main one with the heartbreak.

I suggest trying to spend time away from him. If you let yourself hang out around him, then your emotions will betray you and and you'll still enjoy being with him. You need time to let yourself get over him. If you find yourself thinking about him, try your best to distract yourself. Talk to a friend, write a story, read a book, listen to music, go for a walk, ride your bike, watch tv, chores even, anything that keeps your mind on something else. If you make up your mind quite firmly you're going to let go, often times you can. Usually when I find myself focusing on something I'm trying to forget, I'll stop and say a prayer. It can be long or short, just telling God I want to let go, and ask for Him to help me to let go. Sometimes those prayers can lead to further topics and emotions and soon I've forgotten what I originally started praying about. Journaling is also a good way to vent out emotions and thoughts and get your mind working on other things. 

And while this may not be fun to hear, maybe you should put off romance awhile. You're still really young. The reason age is important is because you can't go anywhere with it anytime soon. You certainly can't get married, and the earlier you start, the more likely you are to run into these situations. You'll just experience a lot of heartbreak by venturing into this. If you get a boyfriend now, do you really think you'll still be with him when you're 18, 19, 20, later than that? If we're honest, very likely not. But you'll still have cared, and by then you'll have given some of your heart away. Save yourself for the one you're meant for for good. Save your heart and mind for someone who will treasure it forever. Wait until you find your forever person. Trust me, it will be well worth it. Besides, doesn't that sound way more romantic then just trying out different guys? God's writing your love story, so it's all taken care of. No need for you to worry.

I hope this helps at least a little, good luck with it!

I kinda have a similar problem. I don't want to date and definitely not now. But because of my background and because of society, the way that folks go on about a gal and a guy saying two words to each other, I have a hard time reminding my mind that I am able to be a friend to guys without it meaning anything more.

There's this one guy who goes to my co-op, he was easy to talk to, we had a few classes together, and we were good friends. It wasn't anything more than that - a friendship - but my brain going off into its own world, and a friend asking me if I "like like" him didn't help. (Said friend and this guy have a complicated relationship mix between friendship and nemisis and because I talked with him like he's a normal person and made a conversation, she asked.) My brain didn't make weird thoughts or connections when I was around him or around other friends, but when I got away from him, I would start questioning what I said and what I did and what he said and did and . . . egh. 

Summer break was an immense relief, and I stopped thinking about him that way. I can think of him as a normal guy friend (as in friend who is a guy.) And he's not coming back to co-op, (I think) and if he is, I'm more prepared. 

Like BHR said, just quit thinking about him. If you have to have a project you have to work with him, then try and act like he's a friend - just that. Avoid him and make little eye contact and conversation as possible without being obvious about what you're doing. It helps a lot, staying away from him and not thinking about him. Try writing down a list of negative qualities - reminds you of why you want to avoid him and helps to see him in a light worse than you picture him. 

Hope this helped!