In a letter to Warren "Cubby" Culbertson, who at the time was running a series of religious counseling sessions for couples at the governor's mansion, the two-term Republican explained he was trying to head off a potential divorce from his wife, Jenny.
The message was obtained by The Associated Press through a public records request.
Mr. Sanford's affair became public in June, when he confessed it after disappearing on a secret trip to Argentina.
He had told his staff he was hiking the Appalachian Trail.
"I simply beg for the chance to figure it ought (sic) privately, please beg her for just the first month after the kids get out of school and if I cant get this done then there will be plenty of time for public humiliation and showing the world I am the guy in the wrong," Mr. Sanford wrote.