I cannot read all of this thread - I have skimmed through the first page.
I suffer from depression, and have done so since I was in my mid teens, when bullying at school left me contemplating suicide.
During my 20s I did work - I trained as a nurse and worked for three years after qualifying, then went to university, got my degree and then got married. Work was always a struggle for me, and looking back, I can see that I was suffering bouts of depression (I wasn't diagnosed until later).
After the birth of each of the dses, I suffered quite badly from postnatal depression, and this is the first time that any form of depression was formally diagnosed, so I thought I was suffering from PND, and that when that got better, I would be free of depression, but I never have been.
I worked again, between ds2 and ds3, but still struggled at work - I felt isolated, anxious, and believed I was a failure and a useless nurse (though I did my job to the best of my abilities, and never did anything less than a reasonably good job).
Since the birth of ds3, I haven't worked (other than some voluntary work and some temporary paid work at ds1's school). I have been, and still am struggling with depression - I was finally diagnosed with depression, rather than PND, so it seems that I got PND because I was already depressed/predisposed to depression.
I have been on antidepressants for years, and am now in psychotherapy, which can be hugely painful, and I struggle with day-to-day life. The depression leaves me feeling permanently tired, unable to concentrate or remember simple things (like people's names). Some days I would like to stay in bed, go to sleep and never wake up. I haven't given in to this, but there are many days when I struggle to do even the basics - have a shower, make myself eat breakfast or make myself a reasonably healthy lunch. I have joined a choir and an art class to get me out of the house and my isolation and loneliness, but even though I usually enjoy these, it is often a real struggle to make myself get out of the house and go.
I have been on holiday during the years when I have had depression, and have enjoyed them, but the depression has always been there, like a black dog on my shoulder. Sometimes he goes away, but he is never far away, and I never know when he will strike again. Even when he is not there, I still feel his effects, and they curtail my activities and enjoyment - everything is in shades of grey.
I wish that those people who have believe that those of us with depression need to just pull up our socks and get back to work, and then we will be fine (because we probably don't have depression at all, we are just skiving, grasping frauds) could walk a few miles in my shoes.
Try living a life where you want to die - not quite enough to do anything concrete about suicide, and not quite enough to be able to put my family through the pain of my suicide, but enough that falling asleep and never waking up again seems like the kindest option for me, and would release me from a life of failure.