Book Idea: Does this type of "book" exist?

My concept is a book that is presented only in the visuals of emails and text messages of a person to a loved on that has passed away.

It is the connection that the living character needs to grasp on to some sort of sanity during the time of loss. It follows the living during the stages of grief and turns into an ongoing therapy where the living person shared their life story moving forward while asking for advice and looking for praise that will never get answered.