Need some advice

I have been living with depression most of my life and soon will be 50. Feeling out of control and my back up against the wall. Have a job that is rewarding but a lot of work. Not handling work situations very well at all. I am very negative with everyone from my family to my co-workers. Not to let some of the people that I work with know how bad I feel have been trying to put the mask on. Not doing well and have tried to explain my problem to my doctor. He seems to think that everything is great, but it is not. I am loosing my temper, and acting totally unprofessional. It is to late after I have done this and spend day after day saying that I am sorry. I am having trouble with just every day interaction with people. It makes me feel terrible and then I beat up on myself for days. Recently have been cutting with a razor blade to get the bad feeling out. Have been trying to find a suport group to go too and not having much luck. It is hard for me to venture out of my safe zone. Normally go home to my house and sit in my chair in the dark. It is getting harder to get up to go to work.

J