here.[Pulls her down on the sofa beside her.] Now I will show you that I too have something to be proud and glad of. It was I who saved Torvald's life.

During their conversation, it is evident that Nora has an inner desire to give herself a role within the family. This is why she confesses to Linde her indiscreet behavior for the sake of Torvald. Already, as early as Act I, there is a strong indication that Nora wants to either get or bestow upon herself some kind of validation.

Nora:[Wags her finger at [Linde]] But “Nora, Nora” is not so silly as you think. We have not been in a position for me to waste money. We have both had to work.

After this first confession, the play begins to crack into more of Nora's secret, as well as into her emotions. This his how we learn that she essentially lives in fear of that moment when Torvald learns the truth. However, Nora contradicts herself in bouts of denial, making herself belief that Torvald will understand; telling herself (through several instances of "talking aloud" to others), that her sacrifice has a purpose, and a reason. This is clearly Nora's way of trying to define her sense of value, despite of the fact that she has none of this value restored in her current situation.

NORA:[appears buried in thought for a short time, then tosses her head]. Nonsense! Trying to frighten me like that!—I am not so silly as he thinks. [Begins to busy herself putting the children's things in order.] And yet—? No, it's impossible! I did it for love's sake.

This being said, we can safely conclude that Nora "had seen it coming". She internally knew that the end will undoubtedly come in the form of Torvald's final rejection. Like she says over and over to herself, "she is not as silly as "he" thinks", and she has been preparing herself mentally for that final moment.

Therefore, when it finally happens, we do not see Nora go into a hysterical plea, nor does she even cry; she, for the first time ever, gracefully admits her flaw, and sums up all the dignity that she had been denied her entire life. Courageously and without a doubt, Nora grows up in that brief moment when all her doubts and fears come to life. However, by now, Nora is ready and tired of pondering, wondering, and lying to herself.

Conclusively, Nora stands up for herself after Torvald's horrible reaction, not as a result of that specific moment when Torvald proved to be an ungrateful husband, but after a lot of consideration and analysis which, in Nora's language, were disguised as jokes or random comments. Henrik Ibsen wanted to make it clear; Nora had live a LIFETIME as a useless part of the family unit and she was already tired of it. She just needed that one extra push to finally break free.