(incomplete)
Because of the understanding disconnect, you might try support to make us feel less sad (which doesn’t help) or provide empathy (better). But because of the lack of understanding, you don’t provide us with the specific kinds of support that would actually help us deal with Depression.
Get your partner / housemate / parent / friend to tell people you can't make it to the Thanksgiving dinner, have them organise to get the kids to school and cook dinner, have them call in sick to your office, etc. Assume you won't go for your afternoon run, or stop to pick up groceries. And this is all ok. You're not well at all.
The next thing is to try and alleviate the symptoms.
What you should be looking for are mechanisms, or drugs, that allow you to focus, and to get things done.
Annoyingly, here's where I run out of suggestions on what to do next. I suffer from major Depression, so it stops me completely in my tracks. And so far only drugs work to get me able to focus again, or to be able to do things again. If I try to force myself to do things while Depressed, it triggers panic attacks - which are even less fun than Depression. So I just sit in front of my computer surfing randomly until the episode passes - which can take anything from a week to a few weeks.
I do know enough to not worry about all the things I'm not doing. And I am lucky enough that over the years, the people in my support system have learned to work around me when I get Depressed and shut down.
If anyone has mechanisms / suggestions that work for them on how to focus or how to get things done or how to get out of minor or major Depression, write in the comments please. One person I know managed to efficiently do a high stress job for a few years while Depressed by rigidly focusing on the job to the exclusion of every thing else - which worked, kinda, but failed in the long term because it lacked balance.
Finally, remember that no matter how you feel, Depression isn't about your capability or how good a person you are. You aren't sad. It's a medical problem that interferes with you ability to do things and it's a real illness. If you can figure out your solution to being able to focus / do things, whether medication like me, or meditation, or running, or whatever works reliably for you, your life stabilises. And that's your answer.