I can't cope anymore?

I think I'm in the throes of depression. My mind is tired, my body is riddled with aches and pains and now my work has piled on the hours in a physically demanding job. I can't cope with it. I'm expected to like it or lump it cos everyone else just gets on with it. I feel so close to just walking out or not showing up. But that makes it difficult for others. But I'm sick of it. I feel so close to doing something stupid or just jacking it all in. But that'll make my life even worse. I can't cope anymore. See my doctor? Done that. Have to wait months for cognitive behaviour therapy. I just feel like dying. Can't do life anymore.