I'm sorry to hear your in such a bad place.
It sounds like the main trigger is financial stressor and environmental? With your DH health too?
I would aim to see what support and routes are available to get a plan to alleviate the financial situation.
Citizens advice have advisors that may point you into the right direction.
Downsizing? Lowering your bills, (once your son moves out i think you would qualify for council tax discount? Water bills can be cut for those on low income? What level of support do you realistically need with you and your husbands health? You can apply for an adult social care assesment through your council website, they would be able to link in with services that could assist you and maybe even qualify for someone to assist with admin duties and helping you sort these issues as your head isn't in the right space.
Do you have any support network to lean on? Any friends?
I although different circumstances was in a very dark place many years ago. I had lost everything and was quite unwell. I had an adult social worker temporarily who took over all the practical aspects of day to day.
Once that pressure is alleviated slightly you can then focus on trying to find your joy. When life seems as bleak and dark as it does for you now, it doesn't come back instantly once the pressure lessens, your outlook does become pessimistic so it will take time to remind yourself.
But to rejoin an old hobby you use to enjoy or find something new to partake in could distract your mind from your life just to have a moment of peace.
This might sound out there, but i actually found meditation groups brilliant, you could chat with other people and I found trying to practice soothing myself, and disconnecting my thoughts helped to put things into perspective and helped me find solutions where I usually can't due to the tumultuous thoughts.
I also found it soothing to know I wasn't the only person in this situation and feeling how I felt.
So if it provides comradery to power you up. My parents are in your situation and similar age. My dad has terminal cancer and they have lost all their retirement funds through a bad investment. Your not alone and you are very much needed and wanted to carry on living, you will never ever see the positive impact you have on others, even the lonely neighbour you always greet to those that love you❤️