In a candid interview today with Matt Lauer on the "Today " show, Elizabeth Edwards, estranged wife of John Edwards, talked about a new addition to her memoir that reflects the breakup of the marriage.

She said she learned the relationship he had with Rielle Hunter was a longer relationship than she had been led to believe. She said he had told her it was a one-night stand. She said she updated "Resilience," now out in paperback, because "It's important the next chapter be present. How I have weathered it and how my famliy has weathered it."

She read a short excerpt from her decision about ending the marriage: "It was a sad and terrifying decision. At the end of 2009, I finally gave up trying."

Edwards said she did watch parts of the the Hunter interview on Oprah Winfrey's show and did not understand how her husband was attracted to "that woman."

Lauer: "In the marriage, was there a straw that broke the camel's back?"

EE: "No, it was a drip, drip drip. I finally I realized we had come down this road and I was not going to find the place where Elizabeth existed anymore."

Matt Lauer and Elizabeth Edwards on the "Today" show.

She did say she had married a 'marvelous' man, but that he's no longer the person whom I married.

Edwards, who has stage 4 breast cancer, said she is on a new chemotherapy routine and says her health is "quite well." She and John Edwards continue to talk and co-parent their children.