Disowning Family Members

Every situation is different and every person will have a different perspective on what happened.
My sister moved away 40 years ago and she has had limited contact with the rest of the family since then. I tried writing to her, and sent gifts when her children were born, but she remained aloof. Her oldest daughter is now about 37 or so, and coincidentally is going to be here for the weekend, primarily to visit my mother who is 91. We hardly know her or my sister's other 2 daughters, largely because my sister hates my mother, something that I only recently learned about from one of my cousins.
As for my asshole brother, he decided about 5 years ago that he no longer considers me to be a part of the family, his choice, and I will not bother trying to change his mind about it. He is very close minded, and believes that he is right about everything, period. Fine with me.
I understand what you're saying, it's sad