work.
I have always tried to be honest and straightforward when the patient was able to understand what is happening. I focus on what the process will be like (if they decide to stop dialysis for instance) and have the fact that it will not be painful at the end. Instead, they will just go to sleep and not wake up.
There have been patients who have had developmental delay and who cannot grasp the process. In these circumstances, I just let them know how much I have enjoyed knowing them. That they are a good person. That it has been a pleasure to be a part of their life. Then, I let the palliative care team do their work with medications etc as the process of death unfolds.
It is not all on your shoulders. If you are involved with palliative care, they have experts who can be of help.
Obviously, it is much more difficult as a parent of a child to have a conversation than it is for a doctor to speak with a patient. If she does not want to talk about it as you mentioned in your post, do not force the conversation. Focus on what you have now and try to make her as comfortable as you can given the circumstances.