I have been in this situation before too. If it were me, I would think first about my reasons for wanting to tell them. Is my motivation for telling them because I am worried someone needs to know how severe his illness is since I will no longer be on the scene? Am I trying to be malicious? Do I want to tell them because I need to feel validated? Maybe I want them to take my side? Maybe I am afraid they are going to judge me? Or perhaps I want to tell them because I feel I owe them something? Is it because I feel guilty for ending the marriage?
Do you know which it is for you?