I am sorry to say this, but your grandmother is full of evil and hatred. There is nothing you can do to change her or get her to curb her behavior because this is who she has always been. It makes no sense to show such hatred toward a little disabled baby, especially one's own flesh and blood.
One wonders why she would want to go to the child's party if she feels that way about her and you, her mother. Just don't invite her. Tell her she is not welcome.
Ignore the guilt trip that is probably coming. You are not required to let her ruin your child's first birthday party just because she is ill and dying. I wonder why your mother let her talk about you like that when you were a child.
I have no children, but I do have an acid-tongued mother, and if I had a child and she insulted her, I would tell her she could either keep her comments to herself or not see her grandchild; I would not just let her hurt my child's feelings. More.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.