You HAVE to get over this guy you're hung up on who's taken. He's taken. He isn't with you and you pining for him and resenting him for being with someone else ISN'T going to help you. It's only going to make it worse.
Stop it. Just stop it right now.
You're not going to be with someone until you start working on yourself. I totally relate to and understand the "well no one's going to love me anyway so what's the point" cycle. It's not true. I have seen allllllll kinds of people with every kind of body and every kind of face and all sorts of personalities end up in relationships. This can happen for you. But it's 100% not going to happen when you're hating yourself this much.
Start working out. Read a book. Get offline for a while. Stop logging into Facebook and other social media sites. Pretend you're a monk on a mission. Turn it into a fucking videogame about your life if you need to. But cut it the fuck out with groove you're stuck in. I KNOW that there's a certain familiar comfort in that groove but you have to get the hell out of it. Think about Kate Kane. Her life was a fucking disaster (and that girl's been through some shit) and she pulled herself together when it really counted.
You really seem to hate a lot of people. If you can't find any other motivation to get yourself together then do it out of revenge against the people you hate. If you work on yourself, you can rise above them.
Stop saying you're not worth anyone's love and affection. It's just complete bullshit. I don't care if you believe it, it's not true even if you repeat it a million times over. You are a person who deserves love and deserves affection but you have to start by giving some to yourself first.
Go read this post if you didn't see it the first time around:
http://www.neogaf.com/forum/showthread.php?t=463116