LEM you simply CANNOT do everything, and by getting SS involved you have taken the essential next step. If she wont engage then I'm afraid you will have to take a step back, just to save yourself.
In other news, DB and I spent an hour at the hospital today, 1 clinical governance manager, 1 nurse who has been brought in to 'sort' out the worst ward she was on, 2 senior geriatric doctors, and 1 other woman who said nothing and I couldnt work out why she was there. The surgery teams declined the invitation to attend - no one knows why, but when asked how we felt about that I said 'not impressed'.
I think they were expecting "why did you let my mum die? we are so grateful for everything you did" Instead they got a drastic, severe clinically analysis of the lack of care over 5 months (DB worked for NHS for almost 40 years), some very tricky questions about lines of responsibility, lack of pain control, lack of dignity and basic kindness for DM, very poor communication, the shambles was that the discharge process, and the lack of support offered to the family.
They had the grace at times to look ashamed, and uncomfortable, and we are promised a follow up letter with indication of areas they will 'work on'. I wait with bated breath... but am not sure it will change anything. Still, she would have been proud of us for standing up for her, and I made some points about the vulnerability of the elderly and the fact that doctors/nurses/HCPs hold the power in that situation and that many other families would not have been able to make as much fuss as we did at the time (out of fear) or to have to tenacity to follow it up like we have.
We went to the pub after, and I am now working my way through lots of 
cockroach and may you all have peaceful weekends.