You are in a very hard predicament. The following may seem harsh, but it really is just intended to give you a different perspective.
You are currently living with a friend, and as your sick pay is not covering all the bills, they are having to carry you. This is VERY difficult to expect from anyone, let alone your own family. So I can understand where they are coming from. Do you have family that can help you? Is it possible to get more sick pay (I'm not sure how that works) through letters from your pdoc, if he feels you really cannot return to work?

Is it just THIS job that stresses you out so much? Maybe you can look at a different job, in a different field, that you could handle much better? Rather look at a job as a distraction, something you can look forward to and can help you get into a routine, than a job?
Once you do get into a job, you will become more financially independent and it will give you confidence and strength