"She couldn't say, 'Well, maybe we'll work through this for years, or maybe we should separate for two years,"' said Hargrave McElroy, a friend, told the magazine for its Aug. 25 issue. "(The cancer) forced her to choose whether to move forward."
Edwards, a two-time Democratic presidential candidate, admitted last week to having a short affair in 2006 with a filmmaker named Rielle Hunter, who was hired that year to produce short videos for his political action committee. The former North Carolina senator denied he was the father of Hunter's five-month old daughter, and offered to take a paternity test to prove it.
Through her attorney, Hunter rejected the idea of such a test and said she has no intention to speak publicly about the affair. Through a spokeswoman, both John and Elizabeth Edwards declined a request for an interview Wednesday.
On The Early Show Thursday, the reporter who wrote the article in People, its Washington correspondent, Sandra Sobieraj Westfall, said to co-anchor Maggie Rodriguez, "He told her it's not his (baby) and she believes him. As her best friend said, she wants to believe him. She does believe him, and that that was really what she wanted most out of him going public -- to knock down those reports, so they could get the truth out, and get on with her life."
"You say she believes him about the child?" Rodriguez asked again.
"That's what I'm told," replied Westfall.
She added that Elizabeth has been taken aback by the public reaction to John's announcement.
Said Westfall, "(Elizabeth's) friend told me (Elizabeth) thought her forgiving him should be enough for everybody else and (Elizabeth) was unprepared for the amount of disgust and how swiftly everything else he had done in his career would be wiped away, and that (Elizabeth is) really reeling from that and afraid what it will do to their legacy as a couple and what their children will inherit."
Edwards has said he both ended the affair and told Elizabeth about his infidelity in 2006. He kicked off his second bid for the White House in New Orleans a few days after Christmas, at an event that Hunter attended and Elizabeth did not.
"The campaign had already gone through its official launch," when John told Elizabeth, Westfall said, " ... and she felt sort of trapped. It was the end of the year 2006, between Christmas and New Year's. They had already done the announcement tour. He was a candidate. And then he drops this bombshell on her. And only in pieces. He told the truth slowly."
But Elizabeth was out campaigning soon thereafter, and continued to do so after the couple disclosed in March that her breast cancer has spread to her bone and could not be cured. In July of that year, the Edwards renewed their vows to celebrate their 30th wedding anniversary in the presence of a small group of friends and family, including their three children.
"There was anguish - excruciating anguish - for her in dealing with this," McElroy said. "She was angry and furious and everything, but at one point she had to make a choice: Do I kick him out, or do we have a 30-year marriage that can be rebuilt."
Edwards brother, Jay Anania, told People that his sister was focused on her children - 8-year-old Jack, 10-year-old Emma Claire and eldest daughter Cate, 26. When he reached her the day after Edwards admitted publicly to the affair, he said Elizabeth asked him to call later because she was reading with Jack.
"Jack reads to her an hour a day as part of his home-schooling," Anania told People. "The world is whizzing around her and she's cool as a cucumber, saying, 'Jack just started, can I call you back?' "
Why did McElroy and Anania go public?
"They wanted to put out there (Elizabeth) wasn't this wind-up doll that went on stage and let the campaign continue out of some sort of craven ambition, but that she really was going through a lot of anguish," Westfall replied.