Sounds a lot like depression. I would seek therapy or help for the suicidal thoughts and feelings of worthlessness. Also, don't lay in bed all day; at least take a shower and put on clean clothes everyday. That will help lift your mood a bit.

Don't feel bad for things you've done in the past. It's the past and you can't change them. You can learn from them to make the future better.
This has to be a conscious change on your part to stop the behavior of self hating. When you have a self hating thought come in your head, reword it as "This mistake of ____________ taught me to __________. I accept myself as I was and how much better I am now." Also, stop hanging out with guys that only want sex from you. Find a guy that genuinely shares your interests.