Thank you everyone who read and posted.
I was so so upset and just wanted to know if the world had gone mad and I really was getting it all wrong.
Sis has her own life and it's fine and lovely and she's been helpful in the past but is busy tbh don't really see her much at all. I've been nearer the parents and that's been fine too. But this time I could sense something different.
She arrived before rest of family. I got her from station all ok let her rest. Next day I was asking for help from her and brothers to sort sleeping arrangements for other family arriving that day.
Kept asking for help but no-one left their comfortable rooms. Sis got her old room from moons ago. So I had to do it alone. Ended up having to take kids to my house so I couldn't sleep in my own bed either.
My DC has severe problems so was also rushing to sort meds and get help for them.
After the outburst she went to sit with the rest of the family and enjoyed Xmas dinner and I sat sobbing. My dad and DC consoled me but the rest were on sis side. I've been having counselling to deal with mum death so I did wonder if jealousy that I'm further along grieving process but calling me a murderer? After mum passed I blamed myself for not paying attention to her as I was consumed by DC problems. So my sis used this against me to confirm that it was all my fault.
Thanks!
I'm sure you are right in saying my sis has not come to terms with my mum's passing but she managed to enjoy her Xmas dinner (that I cooked) quite happily after her accusations. Also her social media is full of events and parties and always with lots of friends so doesn't seem depressed not like my DC anyway. Sorry it's long thanks again for your advice x