Sanford admits affair

South Carolina Gov. Mark Sanford, crying at times, admitted Wednesday to having an extramarital affair with an Argentine woman

"I've been unfaithful to my wife," Sanford said at a state capitol news conference hours after he returned to the country from a visit to his mistress in Argentina.

It began very innocently," he explained, saying he had known the woman for eight years.

But the relationship with somebody he only called a "dear, dear friend" developed into an adulterous relationship in the past year.

He said he seen his mistress three times since they began the affair or, as he put it, "since the whole sparking thing." Sanford said the two met via "a casual email back and forth."

In disclosing his affair, Sanford also announced he was resigning his post as Chairman of the Republican Governor's Association.

Taking questions from reporters, Sanford said his wife knew about the relationship before his trip last week and that "they had been working through this thing for about the last five months."

He shed tears as he explained how helpful one friend had been.

He also choked up when he said: "This has been selfishness on my part."

Sanford's admission caps an extraordinary week in which he was revealed to having been in Argentina and not, as his staff said, hiking on the Appalachian trail.

Before disclosing his relationship, Sanford apologized profusely to a number of family and friends as well as his staff.

"I've let down a lot of people -- that's the bottom line," Sanford said.

In what were at times rambling remarks during an 18-minute news conference, Sanford delved into the nature of sin and explained his affinity for "adventure trips."

He said that he spent "the past five days of my life crying in Argentina so I could repeat it to when I came back here."

He requested a "zone of privacy" for his family, who are out of the capital and in the governor's Sullivan's Island, S.C., beach house.