Hi Simon
I agree with January. When you have support (in whatever form) it can get you through the toughest times. I am sorry that you have to deal with such negativity everday at work. I can relate to your not relating to the people you work with, and I think it's because you have far greater insights and are more sensitive than your co-workers.(A good thing, in my opinion!) I know you asked for suggestions other than "leave that place" , so I am not going to say it.

I think it would make things easier though if you can think to yourself that this isn't a forever situation, it's just a job that you happen to have now. (It doesn't mean you will be there forever

)
I have a friend who was in the same type of situation. He dreaded going to his job everyday because he did not relate to the people there at all. He also had a very negative boss, and he also had an injury that kept him from working (he had a leg injury). His boss and her assistant were much as you describe your boss to be-they told him he couldn't just take off work when he felt like it, and he had responsibilites. (He had a doctor's note and everything!) Well this was kind of a final straw for him. He didn't quit his job right away, he looked around and eventually found a place willing to hire him, and he quit his other job. He is now in a job where he has made plenty of friends that he relates to, and they hang out outside of work all the time. Of course he still gets stressed out every now and then with his new job, but he is far happier and more relaxed than I've ever seen him. I don't mean to go on and on, I just wanted you to know that there is hope, I have witnessed it firsthand!
Best Wishes,
Sujin