I would not give a 6.5 page letter to a T to read in session, especially a stranger. They don't know you at all and I imagine that there is a ton of very personal content and nuance in that letter, which most likely would not be understood correctly or would be misinterpreted. Giving all the details without introduction. I personally would just use my therapy session to discuss the story, your feelings, maybe the letter and give them the opportunity to ask questions.