If it were possible for you to unknow something you know what would it be? Why?

If a "truth" does nothing but cause hurt what is its purpose? I shall give you an example of a truth better left unknown.  A woman buries her husband. At the funeral a "friend" comes up and informs her that her husband was having an affair for years with her best friend. So now the woman has not only lost her husband but will live out the rest of her days in additional sorrow. What does she do with that information? Confront the woman who slept with her husband all those years? What is the benefit to her? If I were that widow it would crush me and I would be left with reliving my life with my husband and questioning the validity of all of it. Thank you for your reply and Happy Sunday. Some truths are better left unknown. I speak only for me not for thee CMI.