Sometimes, we learn to look at an event or a person in a different light. I heard recently that "it isn't a story until something bad happens." The more I have gone over that thought, the more it seems true. We can hear or read a story or see it acted out and as we are wired to do, we immediately assign a 'valence', a weight, to the story as being roughly good or bad. The story of the world war II concentration camps usually gets a "bad" rating and with good reason. The story of recovery from a disease gets a "good" rating.
We have things in our memories that are labeled "good" or "bad". We can look at the story of how we got where we are today as a mixture of positive and negative events and decisions. Sometimes, we learn more or new evidence is uncovered and the label changes. That can be disorienting and painful. If we thought Abraham Lincoln was a hero and we find he did some things that were not good, it can be disconcerting to find our mind and our judgment being revised.
When something tragic or nasty happens, we are often called upon to remember the pain and loss involved. I know that I don't know all the pain and all the loss and I know that even in my own life, I can't stay aware of all the good and all the bad that has happened to me or that I created.
Sometimes, the essence of being aware of myself is said to be improved, if only temporarily by intense concentration on the exact present. At moments when I do that, all my sins, all my mistakes, all my accomplishments, all my triumphs are put aside, shelved, temporarily non-existent. Just because I am not thinking of events in the past does not mean that they didn't exist or that they weren't "good" or "bad". Just because I forget about them doesn't mean their effects are gone or that they didn't matter.
We all have finite and fallible memories and judgments and long biological and personal pasts. The memories, the valences and the judgments all matter, however fleeting and slippery they are.