Here's why this is considered the climax:
* High Stakes: Isabel's decision carries immense weight. She's faced with a moral dilemma: stay loyal to Madame Loisel, who has been kind to her, or betray her to save the life of her brother, Curzon.
* Turning Point: This moment signifies a turning point in the story. It marks Isabel's transition from a passive victim to an active participant in the fight for her freedom.
* Consequence: This action has significant consequences. It leads to Madame Loisel's arrest and imprisonment, and potentially puts Isabel herself in danger.
* Dramatic Tension: The moment is full of dramatic tension. Isabel struggles with her conscience, and her decision is made in a moment of fear and desperation.
While the novel continues after this event, it's this pivotal decision that sets the stage for the final resolution of the story and the future of Isabel's life.