It doesn't say it is mandatory to attend on the letter I have made a doctors appointment for today Some posts say it is correct and some say not I am going to try and call them this morning Thank you for your replies

I had a breakdown in May 2014 after working for 12 years without a break I am sufferring from severe anxiety disorder, have panic attacks, at times agraphobia. I also suffer from back problems after a double slipped disc some time ago. I have received CBT, Intensive CBT and been referred to a psycologist as i have intense problems sleeping and had a number of suicide attempts which I am glad wernt successful. (although at times i wish they were) I was signed on to ESA by my doctor in May 2014 and as of yet, even tho i have telephoned, i have not had my WCA from ATOS 13 months later. Today I received a letter from the jobcentre asking me to attend a work focussed interview to discuss the possibility of me going into paid work. I dont know what to do. I am terrified to attend as i cant cope with face to face situations and the thought of going to work and letting people down or finding out my secret is mortifying. I go out, by cab to help my daughter who is 19 and suffers from severe mental illness, my breakdown was due initially to her illness and trying to support her whilst working. I was sacked from my job after making an error which cost them thousands of pounds on the day my daughter tried to throw herself under a train. I was a pub manager so my work was also my home and we lost that too and was homeless for 9 months 1 month of that my daughter being in a coma. My doctor is supportive but my world is filled with fear and now im terrified i will lose the small amount of benefit i receive if i dont go to an appointment to find work which my doctor and no esa doctor has deemed me capable of doing. I dont know how to handle this and writing this in the vain attempt to get some advice as google searches are coming up with nothing:-( Can anyone help me?