There are no rules in therapy on what to talk and not to talk about. The content of discussions emerges spontaneously and is also coordinated spontaneously between you and your therapist. If you don't want to discuss something, you let the therapist know that, but if the therapist believes that certain things need to be discussed in order for your issues to get resolved, he or she would also let you know that. From that point on, if you and the therapist mutually agree on what you need to work on, the work will proceed, if you fail to reach an agreement, you will have to find a new therapist who would be more on the same page with you.