I'm truly sorry for you and everything that's happened to upset you so much. In the state you appear to be in, I would first of all recommend you get some counselling or go and see a doctor, if you haven't done so already. Everybody has experienced some real heartache in life somewhere down in the line (myself included), and it can be unnerving. But you've got to focus on happy things. Remember to tell yourself that you are worth something, and try to stay positive no matter how difficult it may be. Allow me to elaborate on this brief paragraph:
1. Don't let your past and your adversaries, past or present get in your way, no matter how dreadful or weak they may make you feel. Always underline that the tragedy would be that you'd otherwise be letting them win or ruin your life in the long term. As pap64 said, you can triumph over hardship and painful memories, hard as it may be. Again, seeking help from a doctor or counsellor would be a good idea.
2. Try to think about the lives of the people who have been mean or have snubbed you. Now, I'm not telling you to instantly forgive them with floods of tears and open arms, or go confronting them, because they probably ought to do that themselves. But have a think about it - they were most likely obnoxious because of their own insecurities, and it's really pitiable that they should deal with it in nasty ways. There's the classic case of people feeling upset about their body image in some way or another so that they end up lashing out on larger people (or sometimes skinny, even anorexic people as well

), but there are other cases, especially when it comes to personality and relations with other people. Some are extreme, some are less so. Let me use one ultimately not so terrible yet nonetheless irritating example of someone I'm friends with (there's a reason I use "sorta", read on). He comes a reasonably repressive household and really has problems with showing any enthusiasm and letting himself go. As a result, he acts coldly and sometimes really displays poor communication skills (he describes it as being reserved), is quite critical of anybody who displays any enthusiasm or artistic flair (myself included sometimes

) or lets themselves go, and can definitely be defined as passive aggressive. If he were simply able to be more open and communicate with himself more affectively, then I'm sure that a lot of people would find him a bit better. In short, a lot of the people who have bean quite beastly to you probably have issues themselves.
3. Relating to the last point, we all have our own quirks and eccentricities, positive and negative, and people need to accept them. The negative ones are probably worth suppressing, but the other ones are worth showing. If some people don't accept them, then to hell with them. The whole world is never going to get along with each other, so don't panic. Don't worry about whether people are going to accept every single detail about you, as it's really being
too idealistic.
4. Never think of committing suicide, or harming yourself. However cold people may seem towards you, even those who can be technically classed as loved ones, their lives would be shaken were you to do such a thing. Hope may run dry, and you may just want to crawl up in a hole and die, but life is too precious for it to be intentionally ended.
5. Find an outlet for creativity as a means of expressing yourself, especially something visual (such as art, dance). Join clubs and societies in things that interest you, as (yes, and this sounds a real cliché) they are great for meeting people. And whilst forums are fun, remember that people at places like UD are basically strangers, so don't rely on us that much for friends; it can sometimes be blurring at an overall friendly place like UD, but remember to set up some boundaries between your virtual and real lives (I can understand you wanting to express yourself to us though).
6. Be tactful at the end of the day. I'm sorry if this sounds patronising, but you've got to treat others with respect even if they are horrid. Don't be openly aggressive from the get go, and don't say things that are likely to annoy or upset people. Kill people with kindness; it's a good way to melt people's cold hearts or to piss them off if they're really awful.
7. Take some time each day to congratulate yourself. It really can help. You look like you've been losing weight (you stated so in the photos thread), so that should be one thing to underline at least.
8. Don't freak out at being sad itself. We all get sad for whatever reason, it's only natural, as much as feeling on a real buzz for a day or two may be. Don't get nervous about being sad, because that will only make matters worse. There have been times when I think "omg, I feel so down", which then leads to me thinking "OMG, I FEEL SO DOWN! UH OH!", which eventually becomes "ARRRRGH, JESUS CHRIST SUPERSTAR, I'M SOOOO SAAAAAAD!!! ARRRRRRRGH!!!!".

These sort of things don't last too long (probably a day or two at most normally), but they're not necessary.
In short, take no notice of horrid people, and of the banality of society. The society we live in causes lots of people to get wound up (seriously, my mother, a doctor, is saddened by how many young people are increasingly suffering from mental health issues), and sometimes this comes across in nasty ways. Rise above it.
Take care,
Joe