I have been in this situation before for almost 2 years, and this is what I have learned;
1: Suicide is a stupid idea. I thought about killing myself, and really, I didn't do it because it would require effort to make myself do it.
2: Focus on things in the present. Don't look far ahead. Focus on small, good things you will get to do that day or that week. Give yourself something to look forward to.
3: Just hold on. Everything is tough, but just keep going. Prove that you can survive and pass this time in your life. At the very least, just go to school/work in its monotony, and find things you enjoy doing in your free time and do them.
4: Just remember that it has to get better sometime. If life's a roller coaster, it can't be flat and stuck in the same place and going the same direction all the time. It has to go back up again sometime.
And I, for some reason, want to write some quotes that helped to remind myself that it'd get better;
"It is darkest before the dawn."
-Harold, .hack//Quarantine
"Give up on yourself, and you give up on the world."
-Joshua, The World Ends With You
I think, overall, the most important thing is to keep yourself ocupied with things you love doing. Music also helps a lot!
I hope that some of this helped--I'm not so good at advice--, and I hope you start feeling better!