Surprisingly, K did write my sister!
It was a sincere letter full of feelings for our brother. She said they were soul mates and, maybe in another place and another time, things might have been perfect for them. Whenever they saw each other, she became weak in the knees like a young girl in love!
One thing she did tell my sister was that they were never together sexually. Only once did they get to be alone and talk intimately. They both felt they didn’t want to cheapen the deep love they had for each other.