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(CNN) -- Elizabeth Edwards, the estranged wife of 2004 vice presidential candidate and former North Carolina senator John Edwards, died Tuesday after a lengthy battle with cancer. She was 61.

She died at the family home in Chapel Hill, North Carolina, according to a statement released by the family.

"Today we have lost the comfort of Elizabeth's presence but she remains the heart of this family," the statement said. "We love her and will never know anyone more inspiring or full of life."

Edwards was diagnosed with breast cancer shortly after her husband lost his bid for vice president in November 2004. John Edwards, a one-term Democratic senator, was Massachusetts Sen. John Kerry's running mate.

It was later revealed that she knew before the election she might have cancer, but shielded her husband from the news during the campaign. She immediately underwent treatment, and the cancer was believed to be in remission.

In March 2007 -- at the start her husband's 2008 presidential campaign -- Edwards learned that the cancer had returned and spread.

Dr. Lisa Carey, the oncologist treating Edwards, categorized the cancer as metastatic stage four cancer, largely confined to the bones.

The cancer was diagnosed treatable but not curable, Edwards said.

Despite the diagnosis, Edwards said she was ready to go forward with her husband's bid for the White House.

"Either you push forward with the things that you were doing yesterday or you start dying," she said. "If I had given up everything that my life was about ... I'd let cancer win before it needed to."

"Maybe eventually it will win," she said. "But I'd let it win before I needed to."

John Edwards, unable to compete with the attention focused on then-Sens. Barack Obama and Hillary Clinton, withdrew from the presidential race in January 2008.

Several months later, he admitted that tabloid claims about an extramarital affair with former campaign videographer Rielle Hunter were true. Eventually, he also admitted to fathering a child with Hunter -- an allegation he initially vociferously denied even after conceding the affair.

John Edwards said the affair happened in 2006 while his wife's cancer was in remission. He claimed he informed his wife at the time and asked for her forgiveness.

The couple was criticized by some activists for not revealing the affair prior to his presidential bid, as the news could have damaged Democratic chances if it became publicly known during a general election campaign in which John Edwards was the party's standard bearer.

"This was our private matter, and I frankly wanted it to be private because as painful as it was I did not want to have to play it out on a public stage as well," Elizabeth Edwards said.

The affair appeared to end any future political ambitions the former senator may have had. It also led to the couple's separation.

Elizabeth Edwards was born Mary Elizabeth Anania on July 3, 1949, in Jacksonville, Florida. Her father was a Navy pilot, and in her early years, she attended school in Japan.

She attended the University of North Carolina in Chapel Hill, and met her future husband while studying at UNC's law school.

They spent their first date dancing at a local Holiday Inn, and it ended with John kissing Elizabeth on the forehead.

"It was just really sweet," she said of the kiss. "I wasn't used to men being sweet."

The couple was married July 30, 1977, the Saturday after they took their state bar exams. They had four children: Wade, Cate, Emma Claire, and Jack. Wade Edwards was killed in a car accident in 1996.

Mrs. Edwards worked as a clerk for U.S. District Judge Calvitt Clarke Jr. in Norfolk, Virginia, and was a bankruptcy lawyer in Raleigh.

In 2006, after her initial cancer diagnosis, she wrote "Saving Graces: Finding Solace and Strength from Friends and Strangers," which chronicled the aftermath of her son's death and her battle with the disease.

When her cancer returned in 2007, the couple held a news conference to publicize the information and declare their intention to continue with John Edwards' campaign.

"You can go cower in the corner and hide or you can go out there and stand up for what you believe in," the former senator said. "We have no intentions of cowering in the corner."

In an interview with the Detroit Free Press after her husband admitted to his affair, Elizabeth Edwards said the incident helped her focus on resuming her role as an advocate for the poor and for health care reform. She also said it pushed her to refocus on her role as a mother.

She also said she did not want her husband's tarnished public image to overshadow his role as an advocate for the poor -- particularly in the eyes of her children.

"I have to prepare for the possibility if I die before they are grown" to make them "able to function without an involved, engaged and admiring parent," she said. "So I need to create the picture for them that I want them to have."

In a September interview on "The Nate Berkus Show," Edwards was asked what she sees when she looks at her estranged husband, John Edwards.

"I see the father of my children, and that's very important to me," she said. "Particularly since I have a terminal disease, this is the person who at some point will take over the primary parenting, and it's important to me that he heals, if he needs too."

Asked about forgiveness, Elizabeth Edwards said that's a difficult topic for her.

"It's really hard to use a word like forgiveness but we found a new of interacting with one another that is healthy -- and I think for the kids -- and really easy for us, which is great," she said.

She said living with stage four cancer "is like dancing with a partner who keeps changing."

"Fortunately with the research, it looks like there may be a new drug for me down the line," she said. "My job is to stay alive until they find a cure. I don't think there's any way to live with this diagnosis than to have that kind of optimism."

On Monday, the Edwards family released a statement saying that further cancer treatment would be unproductive.

In a message posted on her Facebook page, Elizabeth Edwards addressed her family and friends:

"The days of our lives, for all of us, are numbered. We know that. And, yes, there are certainly times when we aren't able to muster as much strength and patience as we would like. It's called being human," she wrote.

"But I have found that in the simple act of living with hope, and in the daily effort to have a positive impact in the world, the days I do have are made all the more meaningful and precious. And for that I am grateful. It isn't possible to put into words the love and gratitude I feel to everyone who has and continues to support and inspire me every day. To you I simply say: you know."

CNN's John King contributed to this report.