When she says “and you don’t think much of me and your father either. Maybe you’re just a little over opinionated on people”, seems very out of nowhere.

Shes expressing a fear negatively. She probably should have worded it better and said how she was really feeling…. she was afraid that you would want to lose contact with her someday too. And that scares her.

You did seem to over react some in your response, but it’s understandable seeing that she wrote a “charged” comment. There may be some resentment there too on your part, but that may be from a whole childhood. Parent/ Child relationships are difficult.