Thanks Jelvie. Yes, I have spoken to Dad about it but he just doesn't get it. He will side with her every time - not that I want him to take sides - just to understand what is going on and try to do something about it. I think my Dad is afraid to be alone and so won't do anything about her attitude and behavior towards us. He knows I've had enough of the behavior and where we are at but would rather lose his children than stand up to her.
Unfortunately it is always up to us to make the compromise. I've watched my Dad become a very bitter and angry man in the time they have been together. I hardly recognise him at all any more. Which is why we are even considering the drastic measure of cutting all ties - to protect Abbey from negative mental games being played by SM. I watched her emotionally and mentally abuse my sister and pushed her until she moved out at 15 and I ended up having to fix things and move my sister interstate to live with DH and I.
I want my Dad to be involved in his Granddaughters life - especially as he considers her his only Grandchild (my brother has 4 kids) but I don't want the conflict and negativity from SM. If I cut all ties with her and not my Dad she would make his life so much worse and she has already been the cause of so many of his health problems. When he was in hospital after his heart attack she verbally abused the bejibers out of him on the ward and his blood pressure got so high he blacked out.