Since my childhood, I understood quite well that my grandmother (father's mother) didn't like me.
I had similar experience with my paternal grandma, too but later, we bonded so well, especially when I'd to prove to her and my aunts of my good performance both in higher institution and being well behaved. I was once accused of being pregnant by her one day when she noticed I always spit when I'm sick. It was my mom who understood the situation then but my grandma wasn't accepting the truth until I was taken to the hospital by my dad and they confirmed it was malaria and my sickness that got me spitting out saliva like a pregnant woman.
She was silent when the result came out and that was the last time she accused me of such. Before she died, we were best of friends.
My grandma is still alive and now she likes me also but there is something she can't make up with me because I experienced many things in my childhood just because of her. Even I wished her to see dead also. Now I don't have the intentions to take revenge. I only respect her as an elder. Nothing more.
Your case seems serious also.
!PIZZA