(CNN)-- A former aide to John Edwards testified Tuesday that the then-presidential candidate made a disparaging comment about his mistress after she called to say she was pregnant.
"She was crying, she was distraught, and she needed to speak with Mr. Edwards immediately," Andrew Young told jurors about his conversation in 2007 with Rielle Hunter. "I said, 'Somebody better be pregnant or dying. She said, 'nobody's dying,' " Young recounted.
He said he told Edwards about Hunter's pregnancy. Young quoted Edwards as replying that " 'She's a crazy slut' and there's a 1-in-3 chance it was his child."
Edwards, the Democratic vice presidential nominee in 2004, is accused of using hundreds of thousands of dollars from 101-year-old heiress Rachel "Bunny" Mellon and another donor to conceal his affair with Hunter.
Prosecutors say Edwards broke federal law by accepting about $725,000 from Mellon and more than $200,000 from Fred Baron, a now-deceased Texas lawyer who was his finance chairman. The money was used to pay for Hunter's living and medical expenses, travel and accommodations to keep her out of sight while he made his second White House run in 2008, prosecutors say.
Young, who was the first witness in the trial, said Mellon was an enthusiastic supporter who apologized for not being able to give the campaign more than $1 million.
Edwards is accused of concealing the money from the public and the Federal Election Commission, which polices political contributions, by filing false and misleading campaign disclosure reports.
"This affair was a gamble with exceedingly high stakes," prosecutor David Harbach told jurors during Monday's opening statements. "If the affair went public, it would have destroyed any chance to become president, and he knew it. Two of his most enthusiastic supporters happened to be wealthy, and he knew that, too. He made a choice to accept hundreds of thousands of dollars. He made a choice to break the law."
Edwards admitted his affair with Hunter in 2008, after his presidential ambitions foundered. In 2010, he admitted that he was the father of Hunter's daughter.
Young testified Tuesday that Hunter was upset because Edwards wouldn't return her calls.
"If I don't talk to him immediately, this is over. I'm tired of living a lie. I'm going to go public," Hunter said, according to Young.
The government's star witness said Edwards indicated that Hunter needed to be kept on an allowance.
"$5,000 a month was the typical amount, but there were a couple of times where we gave $12,000 a month," said Young, who is testifying for the prosecution under a cooperation agreement with the hope that he won't be prosecuted. During his testimony, he admitted to being arrested for driving while intoxicated in 2006.
According to Young, Edwards tried to distance himself from the Mellon money of which he was aware while he was interested in becoming U.S. attorney general in a new Democratic administration.
"He said he couldn't know about any of this in case he had to be sworn in for attorney general," Young said.
Young, who is married, once falsely claimed he was the father of Hunter's child as part of the effort to hide Edwards' involvement.
He is the author of "The Politician: An Insider's Account of John Edwards's Pursuit of the Presidency and the Scandal That Brought Him Down," in which he accuses Edwards of using money from his benefactors to maintain his relationship with Hunter.
The defense argues that the money Edwards received from Mellon and Baron was for personal reasons: to protect Edwards' wife, Elizabeth, who was dying of cancer, and his family from public humiliation. Edwards has said his actions were wrong but insisted that they were not illegal.
"This was a fall from grace," defense attorney Allison Van Laningham told jurors. "It was that humiliation he was trying to avoid all along."
Edwards could face up to 30 years in prison if convicted of all six felony and misdemeanor counts against him. Seven of the 16 jurors, four of whom are alternates, are women.
Young said Mellon had a private plane fly him to her Virginia estate in 2006, where she asked what she could do to help Edwards win the White House.
"She felt like he was going to be the savior of America," he testified.
Young said he began to have suspicions about the affair in September 2006, after Hunter had been hired to shoot Edwards' campaign videos. He said he picked up Hunter and Edwards at Washington's Dulles International Airport. For the first time in seven years of working for the former North Carolina senator, Edwards asked him to carry their luggage, Young testified.
Edwards used Young's phone to make several calls to Hunter in the following days, which included a visit to Mellon's home. When Hunter called Young on one of those days to ask about her schedule, he said, he could hear Edwards cough in the background. And at the end of the trip, he said, he and Edwards took her back to Dulles, something he said was never done for campaign staff members.
Edwards' lawyers wasted no time attacking Young's credibility, starting with their opening statements. Van Laningham alleged that Young consulted with three other witnesses about testimony after the witness list was released three weeks ago and portrayed him as a greedy staffer who has said Edwards is his ticket to the top.
Van Laningham also pointed out that Young had his own affair, a one-night stand with a campaign employee.
Experts say the government faces an uphill battle to convict Edwards in a legal field riddled with loopholes. The former senator refused a plea bargain that would have given him a few months in prison but would have allowed him to keep his law license.
His wife, Elizabeth, died of cancer in December 2010. The pair had separated after Edwards acknowledged the paternity of Hunter's child, but Edwards was at her bedside when she died.