Why I Strongly Dislike My Grandmother

I strongly dislike my grandmother. I really, really, strongly dislike my grandmother. I could never hate her because she is my grandmother and she did give birth to the person (no matter how terrible of a person he is) that is half responsible for my existence, but I dislike her. A lot.
When I was really young, like five, my parents got divorced. I only visited my dad and his side of the family until I was about eight. It came to a point where it was kind of like that whole family just dropped off the face of the earth one day. I didn’t really mind though. My dad and I never had the greatest relationship, mostly due to his heavy addiction to drugs and alcohol, but this isn’t about him. It’s about my grandmother. My loving, kind, caring, sweet grandma. Oh, wait. She’s none of those things. After my dad stopped coming around, I at least thought my grandparents would still visit my sisters and I. I mean, they always seemed so loving and nice. I was wrong. But that’s still not the thing that I’m really upset about.
Last weekend, my sister went down with my grandma on my mom’s side to our family’s camper. My grandparents from my dad’s side happen to have a camper in the same campground, but are never down there when we are, so we’ve never had an interaction with them. Until last weekend. My sister was on the golf cart and came face-to-face with our grandparents for the first time in over ten years. Someone pointed out to them that my sister was their granddaughter, and my grandma said that she needed to leave because she didn’t “associate with those people”. I’m sorry, what? Your own granddaughter, who you haven’t seen in ten years, and you refuse to talk to her? It may just be me, but I think that’s a little ridiculous. What infuriates me is that she made it sound like we had somehow wronged her. That when we were young children, at the ages of five and eight, we had done something to make her despise us. And she couldn’t even refer to us as her family, who share the same blood, but as “those people”. Like “those people who I can't even refer to by name because the thought of saying and accepting that they are my granddaughters may make me physically ill”. We were kids that got stuck in the middle of an ugly divorce, and somehow, we have to suffer? We have to be blamed for things we can’t be held responsible for because we had no decision in the matter? We're the ones who had to grow up without our dad and grandparents because they decided they didn't want us anymore, but somehow that's our fault and we should feel bad for you? I never thought it was possible for someone to hate their own grandchildren, but I guess you learn something new every day.