To move on or try to get him back?

There's one problem with me - i realize too late that i actually like somebody.
There was this boy who wanted to have a relationship with me. Although.. we were at a party and when he fell asleep i made out with one of his best friends. Few days later I admitted it and he was still willing to have a relationship with me. That day I finally decided to say yes to him but at night I made out with another boy. I admitted that too and he was STILL willing to have a relationship with a girl like me, who back then had know idea what she wanted.
Anyway, I said yes to him but i was a mess and for some reason i started to regret it, so in the morning i broke up (if you could say it) with him. Then.. for a month i was very depressed and i missed him a lot. He didn't want anything to do with me.
2 months later we were at a party where he found his girlfriend and when they broke up 2 months later, i saw him and he invited me to a party. He was flirting with me but my feelings were gone and yes, i made out with ANOTHER guy. (Only that one he doesn't know about.)
I have no idea where my mind was back then. I admit that i was kind of slutty, although i didn't sleep with any of those guys. It was again 2 months ago. Lately i've been trying to get to know different guys and the more guys i meet, the more i realize that he could actually be the one i would fall in love with. We are so alike and just.. he has the type of personality that attracts me.
Now I've been missing him A LOT. I'm thinking about him every day. I'm actually starting to go crazy. I see him every day and i try to hold my tears back so hard. I had so many chances and i didn't take any of them. I was stupid and i was still finding out what the relationship world is about.
I talked to him like a week ago. He asked for a party and then he said for fun that he could come to my place and have sex with me (me and him haven't done it). When i see him at school every day, he smiles at me, makes silly faces, etc.
Still, I get it - he can only see me as a slutty girl now. But if i could just explain everything to him.. i have so many things to tell him but i just don't know how. I would never ever cheat on him. (when i made out with another boys, we weren't actually dating so yeah)
So... what do you think about my situation? Should i tell him anything or just forget it and try to move on?
And please, anybody, don't judge me. I know what i've done and yes, it really makes me feel like shit and i hate myself for that.

Its only kissing, calm down! Thats not slutty behaviour.

Don't throw yourself at him, otherwise you'll be used. Get your esteem and confidence back and flirt with him a bit, get friendly with him again, allow him to like you without rushing into anything.
He'll notice the change in you when you start hanging out again. Then if/when he asks you out don't blow it! ;-)

You really shouldn't put this other guy through a roller coaster of emotions if he wants something serious. But if he just wants a fling, then go for it.

And yes, you're young, you're exploring, and you kissed a few guys. Nothing to lose sleep over at this point. But if you decide to date someone exclusively, you need to stick with it.