Okay. I'm coming in late on this, but here I go anyway.. just cuz there's a soft spot in my heart for you DY
But first I must say:
1) who knew Bondi had insight like that? I thought he was just a simpsons encyclopedia.
2) who knew Gnappy had insight like that? I thought he was just a simpsons encyclopedia.
3) CM, that was fucking Hilarious!!!! the clown beating story was great... but the reasoning behind it is killer... just so he has to tell the story. I love it. But then you go and edit a picture and post it. You are tops, man!! Well done!!
Okay, DY, here's my dribble for ya. I won't rehash all the good things that everyone else here has told you. but I will point out one or two things that everyone missed. and as a side note, since 7th grade all my really close friends have been female, so I hvae a lot of background with this kind of thing.
Your post that explains what happened also explains the "why." You said (through inferences anyway) that this guy was basically a loser with no direction. His family was not a positive influence in the get a life department and aspirations likely were never anything he was brought up with. So now here comes you, a gorgoeous, fun-loving girl with personality and wit who actually gives a shit about him. It seems like he sees being with you as work. He can be with you and go to classes, get a job, be in an intelligent adult relationship as opposed to a few week relationship built on nothing more deep than physical attraction... or he can live status quo with his mom where there are no demands or expectations. He has lived his life surrounded by people who just don't give a shit. I betcha his dad abused his mother and that's why he thought it was okay to abuse you. And look at where his mom ended up... believing she was no better than working a shithole job and living in a dead-end area. looking at his life with his parents is like looking in the crystal ball for his future life. He is going nowhere... and he chooses to go nowhere. Status quo is easy for him and that's all that will ever make him happy. Aspiring anything more would be work for him and he's never had to work for anything before because his parents probably never gave a shit anyway. His complacency will never change.
Now, as for the 3-some thing 2 weeks later. I guarantee he had that set up before he left... that probalby was the stimulus to his leaving. He saw an opportunity and he saw you as a roadblock. Because he has no perception of a normal human being's feelings he acted on impulse and took the shortest route to acheiving his goal of hanging out with those girls. He couldn't work his way into that 3some with you around, hence his comment about having to spend so much time with you, so he decided to remove the obstacle... you.
Now, you can continue to look in the past all you want... that will help you to understand the pain... but that's only half of it. The most important thing you need to figure out is how to deal with and get over the pain... which is all things you must do in the future.. Rehashing and sorting out the details is not pain relief... it is only pain disclosure.
You next step is to find what makes YOU happy!!! and making others happy is not the right answer. if you like to read, then read. If you like to take nude pictures of yourself and post them here, then do just that. if you like to meet new people for the sake of friendship, then do that and enjoy that knowing that you're buidling alliances/comrades for all situations, good and bad. I would also suggest prayer and meditation
I think a good next step would be to take your classes and enjoy that, along with reading and other activities you like. Confide and take comfort in your family... who will ALWAYS be there for you. Meet friends at school. Study-buddies are a great way to meet people. and a bit of advice about meeting people at school. If a guy from class asks you out, he's likely only attracted to you phsycially. If a guy from class wants to study with you, or sit with you at lunch and have an actual give-and-take conversation, he's likely after attracted to you intellectually... and physically (any man would be a complete fool not to be attracted to you phsycially).
Okay. I should probably end this cuz this post is getting long (even for me). And the bossman is lurking around the corner and I know he knows I'm on the Internet screwing around instead of actually working.
Look how many people are here who care about you, DY. you're a great person. Dont give anyone the power to make you think otherwise and certainly don't let anyone but you control your mood.
You're in my thoughts and prayers.

And on another note...
I'm pretty sure (like 99%) that if you ask any one of us you'd find that if you had any problem... you could talk to any of us and we'd be an ear to you. I'm 100% positive that I would be willing... Cman would too just because he's Cman... anyone who comes up with murderous clowns has to be trustworthy