At the end of the act, Helmer talks with Nora about Krogstad. What upsets Nora so much about this conversation?

I can't tell you the page number because there are literally hundreds of publications of this novel. Mine is in an obscure book of plays around 20 years old. Nora asks about the nature of Krogstad’s past indiscretion, and Torvald reveals that it was forgery. He condemns Krogstad in strong terms for failing to admit it. Torvald admits that he would have forgiven the man had Krogstad owned up to his lie. He suggests that such moral hypocrisy would even infect Krogstad’s family. Torvald makes Nora promise never to plead Krogstad’s case again. He also reveals his intention to fire Krogstad from the bank.