In this excerpt, we learn that Nora has been feeling extremely upset recently. She knows that her plot has been discovered and her future is in jeopardy. Krogstad asks her whether she has thought about running away from home. He also asks whether she has thought of something even worse. She admits that she has, but that she is not brave enough. The fact that neither one of them mention this "worse" thing indicates that Nora has been considering killing herself.
In the excerpt, it is inferred that D. Nora is considering killing herself.
After Krogstad discovers that Nora has committed fraud against him, she realizes he could use that information to blackmail her husband. In this way, he would not lose his job but he would get a higher position. So Nora thinks about suicide as the only way to escape, but Krogstad warns her he will write Torvald a letter telling everything anyways.
