Hecubas - you sound seriously, seriously depressed sweetheart.
I've been there and its a terrible and dark place. Its not unusual when you're there to remember every awful thing that has ever been said or done to you as your mind is trying to get everything to back up its depressed mode. Feeling worthless and helpless and that you are to blame for everything and that you deserve punishment are just some of the horrible things that this illness does to you.
If you trap your hand in the door, all your head can think about it the pain in your hand and you can't really do anything until its gone. Its the same with depression, until you tackle it, its all that you can see.
You are an intelligent woman and a caring mother who has fallen on hard times and has become ill. Not some awful pariah who deserves punishment.
Forget everything you have to do and focus on one thing at a time. You need to get to your GP to sort out your anti-depressants, either to find one that works better for you or to increase the dose and also get on the waiting list for counselling as having a safe place where you can get everything off your mind to someone trained to help is invaluable. If you are feeling like harming yourself in any way then go to A&E where they will look after you and get you a professional to talk to.
This is a severe depression you're in and you're going to need intervention to help you get out of it. Tackle this first and the rest will fall into place. This is coming from someone who has been signed off since Jan to deal with the same problem, though thankfully I caught myself spiraling before it got to the black place where you are now.
Take care of yourself. Please go and get help x