First off, call the
Samaritans tonight. They will give you a listening ear and some first level counselling to get you through your immediate crisis, and if your troubles continue, they'll always be there for you.
In the morning, phone your doctor and make an appointment to see him or her. Depression is a very real illness that the medical profession takes a lot more seriously than it used to.
Please don't do nothing, and don't do anything silly either. Your life is far too precious to end, no matter how sh1te it might feel to you right now.