I definitely think you need some mental health support. I don't want to say that your line of thinking is not normal, because that just sounds catastrophic, but it is a-typical, and it sounds like a multi-faceted approach to recovery will really help you.
I know you don't want to give too many details, but what did you enjoy doing about the job? Or rather, if you were to find another job, what would you hope it entails? What are your strengths? What makes you feel like you have accomplished something? You don't have to tell us here, but I'm just trying to see if it's possible for you to build the foundations for a new future pathway.
I am autistic, and a very obvious black and white thinker, and I find it so easy to spiral when anxiety and paranoia take hold. I didn't find CBT overly helpful, but some of the things it did provide I still practice to this day.
One of them is scheduling worry time.
I give myself half an hour a day to be as neurotic as I need to be about things that other people don't seem to be phased by. Sometimes this is with a trusted person, and sometimes it's just with a notepad. Then, at the end of it, I separate it into 2 categories.
Can something be done about this? No, let it go then or Yes.
If yes, when can something be done about it? Then I bullet point all of my worries in priority order, and then I tick them off as I sort them out.
Each day, I revisit any left over worries from the day before, and they get added to the list.
I find that a lot of the things I worry over, I can't do anything about so they end up just getting thrown away and forgotten. Sometimes something can be done, but in order to get there, there are other steps involved, and it can take some time, and I have to learn to have patience with myself and not get carried away, but it has turned worry and panic into anticipation and excitement, and even finally feeling accomplished once I achieve them.
This has really helped me curb my anxiety and low mood when the spirals start to happen. Could something like this work for you? Do you think that you could give some CBT a go?