ESA CAPABILITY FOR WORK QUESTIONNAIRE

Hi everyone,
I’m looking for advice as I’ve just received a letter from the DWP requiring me to fill in a work capability questionnaire.
I am in the work related activity group and have been since 2013 but haven’t had to go into the JC for any interviews since then. 
I’m so worried as I know I’m not capable of coping with work right now, I have a lot of problems and I know how these medical s go. I had one medical back in 2012, it went awful, I was unprepared, the examiner was insensitive and lied about so much stuff when I got the report back.
I suffer with BPD, anger problems and I’m also heavily reliant on alcohol. I take a lot of medication (depakote, duloxetine, quetiapine, tramadol and have just also been given sleeping tablets) and for the best part of every day I just feel terrible. I don’t really go out and when I do it’s with my partner, I can’t face going out alone. I feel terrible for the burden I leave on my partner as I know how difficult I am. I am going through a difficult time mentally as it is at the moment as my anxiety has peaked over the last couple of months. I’ve been having suicidal thoughts lately too but I find ir difficult to get help with this too as my GP generally can’t offer me a lot of help since I’ve not attempted suicide. The answer is always more medication and I’m left to it.
I’ve struggled with this for years, I know how swamped the nhs is and for this I don’t feel like I get the help I need, I see my psychiatrist once every 3 months and that’s how it’s always been. I’m terrified of this medical because I know how harsh they are and how they just want to fail everyone who walks through the door.
I’d appreciate any help that people could offer with regards to filling in the form, what to write, what to provide etc.
I read if you fail the medical you have to claim JSA and I don’t know how I could do that because I’m so unstable I just know it isn’t an option for me.