Explaining the film

Since everyone has his own interpretation of this film I feel there are too many far-fetched explanations out there.The book Nocturnal Animals is Tony's a way of saying how Susan made him feel when she left him.And through the book you can see what will happen in the future.When Susan tells Tony he should go back to school and not to write about himself she kills his "wife and daughter" or the thing he holds the dearest his literature.This is proven by the symbol of the red couch.And for the ending,Susan considered Tony weak like Ray thought Tony won't shoot him. When Tony kills Ray it's portayed in real life as Tony leaving Susan waiting in the restaurant.He is no longer weak but it changed him thus he killed the weak version of himself.Tried to to keep it short...Please tell me your opinion.