You made a very good point

Which shows the limitation of one's understanding of stories. When I read the book, I was struck by Zeena's selfishness and insensitivity to Mattie's situation. Once that kind of impression took hold in my mind, I couldn't remove it. I read the book only once and thought it an excellent book and a moving story.

Based on what you saw in the movie and other sources, I think you are correct. What I wrote reflects more of my feelings at the times when I read the stories.

Thanks for reading and the thoughtful analysis.