There are many possible causes for what you're going through, a lot of them already listed and needing immediate psychiatric and psychological treatment. This is good advice, especially to help with the mental aspect of things so that you don't end your life prematurely.

But one thing no one mentioned, that i'm a bit surprised about because you mention falling asleep during work, waking up not feeling refreshed, etc. is a sleep study. It's very very possible you might have a sleep disorder. You sound very much like i did in the early stages of my own sleep disorder, before my life completely fell apart, before multiple suicide attempts, before becoming homeless, before moving back home with my parents, before 9 years after symptoms first started, with health insurance again due to ACA in the US i finally saw a competent doctor and got properly evaluated, and found out i had developed narcolepsy.

Any number of other sleep disorders could cause your symptoms too, of depression and anxiety, as well as the other issues, with conditions like sleep apnea being the most common.

Please please speak to your GP and get a sleep study done, if you haven't had one done already. It's definitely worth doing before you make any final decisions, and it just might save your life.