Have been advised by the expert Mners here this needs a new thread....
So here it is.
Have printed off todays' email from the sister from hell for friends DH who is dropping in later to read, probably drink and discuss.....
Thanks so much for all your replies.... You ladies are helping me reain sane when I really really really want to lose the plot spectacularly!
Am about to sort dinner and stuff so wll update further later when friends DH has been and I know what to do if anything....
DF just read the email and is "do recycling and smash stuff" to "absorb before he comes over really South London.... 
. He is furious at the sister even referring to our recent loss amongst other comments in the message and wants a level head before our friend arrives...
All will be fine..... Will update later.