I can relate to this. I spent years in jobs where I would have progressively worse nervous breakdowns at the end of each one.
The KEY to surviving in this is to get support. Find a good therapist. You may not have depression or any particular mental health problems, but having someone you can turn to whether you see them every week, once a month, something. Find someone.
Scale back other commitments as far as physically possible. Make your life small so you can just turn up and work.
THEN... you need a strategy. Once you've committed to just doing an awful job and you've got some support, set goals, think ahead and make a realistic plan. Consider ALL options. The ideal thing in your situation is to either find a skill you can do freelance OR a job that eventually would pay well enough for you to live off a part time salary in relative comfort. You may go through some dark days before getting to that, but it is honestly so, so worth it. As soon as you start getting in a half way manageable situation work wise, your whole personality and outlook starts to change back and you feel like yourself again. This is why having a therapist to turn to during this process is so crucial.
Don't give up.
Other things you can do are looking at ways of making your home a real sanctuary. Don't socialise if you don't feel like it. I had to be very single minded that I just worked and came home, ate well and did exercise dvds at home. I did nothing else for maybe 3 years. Now I work part-time hours from home and it's enough to be comfortable.
I have been pushed to suicidal thoughts through this process and think if I'd have had the therapist I eventually got, all through that process, it would have been less severe.
Another thing to consider is consistency, over time if you limit the changes to housing, routine and work, this eventually makes things a bit easier too. So avoid making lots of changes. Consider things first.
It can get better with a proper plan but I won't lie, it may be pretty tough. It's worth it for the relief you get when it starts going in the right direction.