It's a long time, I ran from our house twice and left when I was 19. It takes every few years for me to write my mother she behaved badly and I don't want to stay in touch. She crawls back in my life in some time and within few years tries to bully me again. She's like a pubescent kid. It's difficult to understand what traumas she had, but also protect myself from this utter bullshit. She believes I'm wrong. But now my brother who lives there chased away second fiancee. Including me, they destroyed third young woman who ran away. I don't want to stay in touch with this.
Discussion
I think the best question to ask is...
"what good would being in touch with them bring me and my part of the family?"
If the net good is negative (receiving bad vibes, anxiety and worry from it), then the best action is to keep your distance.
I hate to be one to recommend that family members stay apart, but I also know from experience how much worry and bother some people can bring into your life.
It's for our kids to have a grandma. Nothing else. She never even borrowed them or took care. We keep it extremely low, just birthdays and Christmas. That seems to work. However dealing with their bs is disappointing and tiring even three times a year.