I have some suggestions, for what they're worth. I can't begin to imagine what you're experiencing, but I can definitely relate to some of the things you're going through, albeit on a much less serious scale.
Take up a hobby, something you can preferably do without relying on other people. Anything from watching TV to reading to being artistic. The most important thing is that it means you always have an escape, something to relax with and feel good about. Personally I'd recommend something like comedies or witty books - you want to make yourself feel better about life, not worse. There are times when I feel like giving up on everything, but I will relax for as long as it takes and I will feel better about it. An important point is that it becomes something stable in an unstable world, something you can rely on.
Sports/ exercise and a healthy diet. It may seem trivial, but a healthy body does wonders for a healthy mind. Sleep is also essential. If you're getting stressed, take some time out immediately instead of letting it build up.
Rely on your friends, whether you feel like you want to make it through alone or that you may be too much of a burden. Sure, don't actively pressure them with everything, but if they've stuck around so far then they're good friends who will help you however they can. It feels great to just let out all your feelings, even if you may need to apologise to your friends later for being so difficult. They'll understand.
I've never had medication, and I know they can have side effects, but honestly they should help a lot. A combination of therapy and medicine will do you good, and if you can't see the good, then know it'll get worse if you stop. Psychiatry has developed a lot, and it can be very successful.
The last is to (probably when your situation gets better) perhaps do some community service. Helping others in such a way seems artificial, but if it's by doing something you love (I taught computing to the elderly) then you'll love the job and love being appreciated by other people.
I hope that at least some of my suggestions will help you, but I will say that by coming here and asking for help, you haven't lost all hope. Well done - persevere!