I've had several bouts of depression since age 13 and it's not something that I would wish on my worst enemy. It's absolutely awful. Take no notice of those who've never suffered with it and tell you to snap out of it - if you could snap out of it you would have done.
It will fade in time, but it might take months. I learned coping strategies for when it's really bad. Sitting on the loo actually helps!
Try to replace those grey morbid thoughts with colourful images, say of flowers or of 50's American cars, anything you like will do. Avoid introspection like the plague. Be careful whom you confide in. Exercise as much as you can. Up your vitamin intake, especially vitamin C. Socialise as much as you're able.
You'll get there, I'm sure.