I don't have to convince her of my reality or who is right/wrong. There are things we both did that contributed to the relationship failing. And, in the letter I invite her to call me if she wishes. This letter ends the entire experience for me and gives her an opportunity to understand.
Actually, talking might put her on the defensive. I plan to say a few words when I give it to her and the letter ends very positively. I have had two other therapists tell me they would be open to such a letter as they would want to know what was going on with me during the time and how they could have helped. If she doesn't see it that way, then she's in the wrong profession.