She may be letting you decide when you are ready to work on it. If it was upsetting when it came up before, maybe you weren't ready then, and you are the only one who can know when you are ready. Otherwise, things that need to be worked on do have a way of coming back up sooner or later. Something that you will talk about will relate to it in some way, and you will come face to face with it again. She could also be counting on that. It is your process, and pushing you to talk about something if you aren't ready or don't want to could feel too pushy and even intimidating or scary. It really is up to you.