(CNN) -- Elizabeth Edwards, the wife of two-time presidential hopeful John Edwards, does not know whether he fathered a child during his affair with a campaign staffer, she says in an interview that is to air this week.
Elizabeth Edwards says she believes that her husband has had no other affairs.
"I have seen a picture of the baby. I have no idea. It doesn't look like my children, but I don't have any idea," she said in an exclusive interview with Oprah Winfrey to air Thursday.
Winfrey's Harpo Productions Inc. provided CNN with several preview clips.
John Edwards admitted in August that he had had an affair with Rielle Hunter, then 42. Hunter was hired to make a movie about Edwards, then making his second try for the Democratic presidential nomination.
The former senator has denied that Hunter's baby is his.
He told his wife that Hunter approached him at a hotel, Elizabeth Edwards said.
"She was standing in front of the hotel and said to him: 'You are so hot.' I can't deliver it, because I don't know how to deliver such lines," she told Winfrey. "But 'You are so hot' are the words she said to him." 
Watch Edwards open up about her husband's affair »
She said she had asked Edwards for only one gift when they got married: that he not have affairs.
"I wanted him to be faithful to me. It was enormously important to me," she said.
She said she believed that the Hunter affair was her husband's only infidelity, adding, "I want to believe that, you know."
Winfrey's company provided a brief clip of the talk show host standing with both John and Elizabeth Edwards, but there was no sound.
John Edwards is under federal investigation over $114,000 in payments to Hunter's production company. Using money from a political action committee for personal matters is a crime. Edwards denies wrongdoing.
Elizabeth Edwards is promoting her new book, "Resilience."
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