I have been in this situation, at 20 years old, too many times.
I was in this state after having a termination then again recently after becoming homeless.
But, if theres one thing I know about life its that you never know whats round the corner. I was ready to give it all up a few weeks ago, couldn't see any way out, then I found out that I was pregnant and that was my turning point. And I know that even when things seem unbearable things will happen that make them bearable again.
You seem to be suffering from depression, I have personal experience with this illness, and the absolute best thing you can do is to see your GP. They dont just dole out meds, they can also do counselling or therapy which I would recommend, having seen first hand the difference that it can make.
If you are feeling suicidal give the samaritans a ring, also not sure where in the country you are but there is a place in London called Maytree which is worth a look at.
Also online there is a fantastic community called 7cupsoftea where you can annonymously talk about your problems with a trained listener. I found that becoming a listener helped me loads. Also organisations like mind and rethink are worth contacting.
There is always light at the end of the tunnel, even if you can't see it from where you're sat.
Even if you feel like you have no friends or family, you would be surprised at how much people want to help, given the chance. Churches are often full of friendly and helpful people even if you aren't of a particular faith.