Author and memoirist , Tomas Gonzalez speaks to this in an interview which I have excerpted here.
“I  think when you write something about something (that) happened you create a universe of fiction, because it is fiction. I don’t try to teach anything to the reader, actually what I would like to happen is that the reader can live in that universe for a while and to be present there and share in the tragedy and the beauty of what happened.

I think that everything in a way is fiction. The memory is a fiction work of the imagination. You can say that I am writing exactly what happened or I remembered exactly what happened but actually you have to recreate it. You cannot know the real reality. The thing you know is what you make  out of memory and that is the most you can get close to reality.

So the truth is you cannot know the truth. It is not invention, it’s like the creation of another reality that stands by itself .and has reality, more reality if you will, than the real reality that dissolves quite fast. The people that were in that story they get distracted they go on with their lives and the story little by little decomposes. What really happened   so you have to recreate it and that recreation becomes more real than the real events.”