He continued to insist he did not use money from state coffers to finance his romantic trysts. He told the AP he flew coach for his two meetings with Chapur in New York last year, and paid for hotels in cash. Last week, he said he would reimburse the state for last year's commerce trip, but insisted he didn't do anything illegal.
When Jenny Sanford, his wife of 20 years, discovered the affair, the two went into counseling and went with a spiritual adviser to New York to break off the extramarital relationship, he said.
But Sanford flew to Buenos Aires a week and a half ago to see his mistress without telling his family, friends, security detail or staff, instead telling them he planned to go hiking on the Appalachian Trail.
Jenny Sanford said she was devastated when she found out about her husband's secret trip.
"He was told in no uncertain terms not to see her," she told The Associated Press Saturday. "I was hoping he was on the Appalachian Trail. But I was not worried about his safety. I was hoping he was doing some real soul searching somewhere and devastated to find out it was Argentina. It's tragic."
On Monday, Sanford made his second appearance after the announcement at a state budget board meeting. He apologized again to his staff for "letting you down" and said he was sorry about the affair. He also reaffirmed his decision to stay in office.
Chapur publicly acknowledged their relationship Sunday in a statement read on Argentine TV.
Chapur remains under the radar because of intense media scrutiny surrounding her. But in a brief statement conveyed through a television report on Buenos Aires' C5N channel, she said she indeed was involved with Sanford and that the published e-mail correspondence between the two was obtained from her account by a "hacker."
The former journalist did not directly acknowledge the affair or mention the embattled governor's name, saying she won't speak about her private life, which has already been made too public and painful. But her statement offered extensive details about how "the author of this evil action" broke into her e-mail account. She denied that the hacker was a friend of hers.
Chapur's friends and colleagues told ABC News she is a sophisticated and intelligent woman, and that the relationship between the two was simply a matter of love.
The governor, who said he initially considered resigning, is holding on firmly to his turf, saying he will complete his remaining 18 months in office in full and work to repair both his public and private relationships. Sanford told The Associated Press that he spoke with close spiritual and political associates who advised him to fight to restore the public's and his family's trust in him.
"Given everything that has gone on, it's obviously something he considered, but he's determined to serve out his term," Joel Sawyer, Sanford's communication director told ABC News Sunday.
At least one member of Sanford's own party called loudly for a criminal investigation into whether the governor broke the law by not informing his lieutenant governor -- who would be in charge in case of emergency -- of his departure and using state money to finance his trips to see his mistress.