I felt sorrow reading this story today. I come from a family of broken relationships also. You didn’t ask, but A few things I would like to tell you from my perspective. You listed all of the sibling interactions back to you grandmother, as I recall. My advice is not to pass this information on to you children. Even the hard one about your own sister and yourself. IT is so difficult to understand as a child, but easy to copy from your Mom, Grandmother, and other loved ones.
It makes holding a grudge easy thing to do in their mind, drawing up sides to keep one of them happy. So hard for young people learning to love and accept one another. Let us break that ‘acceptable pattern’ for the children. When they are old enough to question you and want real answers, you should explain how important family and healthy family relationships are, and how you feel lost from losing that. I didn’t do all this right in my family, but from my perspective now of 70 years, I wish I had. It was hard for my children, it was hard for me. Hard for my parents and grandparents who are all dead now, but memories are still their. Don’t wait too long to go down that mountain to your sister, lives are frail and we should treasure and each day God gives us. I am praying for a restored relationship for you and your sister.