Jenny Sanford said her estranged husband, Gov. Mark Sanford, insisted they skip the part about marital fidelity in their wedding vows 20 years ago.
The soon-to-be-ex-first lady, who has filed for divorce, also says the breaking point for her was the steamy e-mails between the governor and his lover, published in The State.
Jenny Sanford makes those and other revelations in an ABC News interview scheduled to air Friday night at 10.
The broadcast is on the same day her book, "Staying True," will be released. The book is billed as an "inspirational memoir" recounting the Sanfords' courtship, marriage and the affair that put the couple in divorce court.
Jenny Sanford tells ABC News' Barbara Walters she thought Mark Sanford's reluctance to pledge fidelity was probably a case of cold feet.
"It bothered me to some extent, but . . . we were very young; we were in love," she said. "I questioned it, but I got past it . . . along with other doubts that I had."
Jenny Sanford has said publicly she discovered her husband's affair in December 2008, and the couple struggled with it for months after.
Last June, the couple agreed to a secret, trial separation. They also agreed to one condition: Gov. Sanford would not see his Argentine lover.
When questions arose about Sanford's whereabouts, The State - having obtained e-mails between Sanford and his lover - met the governor at the Atlanta airport as he returned from Argentina.
Sanford had told his staff he'd been hiking the Appalachian Trail. At the airport, he told The State that he had been driving the Argentine coast.
But Sanford admitted the affair publicly after The State confronted him with the e-mails containing intimate details of an affair.
Jenny Sanford said the publication of the e-mails was a tipping point.
"He talks about her tan lines and parts of her body in the e-mails . . . nothing, nothing you ever want your children to read on the Web."
She tells ABC News three of her four sons read the e-mails.
"Their world's been turned upside-down as well. It is something that is now a part of their lives. ... They're not happy. They're not proud. ... It just ripped me up, to see them reading these e-mails, and to see them have to grow up so fast."
Jenny Sanford on TV
Sanford segment is at approximately the 17:00 mark