02/10/2012 12:23 pm ET

Chris Matthews On Mimi Alford JFK Affair: 'I Really Believe Her Story' (VIDEO)

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Chris Matthews revealed that he believes Mimi Alford, the former White House intern who claims she had an affair with President Kennedy when she was 19, on Friday's "Morning Joe."

Alford recently disclosed stunning details about their 18-month relationship in a new book. She said that she lost her virginity to JFK and that she spent nights in the White House with him when the First Lady was out of town.

Matthews, who penned a biography of JFK, has expressed his ardent admiration of the late president before. But on Friday, even he denounced Kennedy's alleged actions. "There's no defense of it," he said.

He called aspects of JFK's personality "indefensible," and blamed the president's philandering on his "cold detachment" from people's feelings. Matthews described his ability to compartmentalize parts of his life as "inhuman."

Joe Scarborough said that Alford's story did not surprise him, and cited rumors about the president's affairs with two other White House interns and Joe Kennedy's advances toward his sons' dates.

Matthews said that he met Alford forty years ago, and did not doubt her claims. "When I read her account, it's dream-like and it doesn't seem real, but it did happen," he said. "I really believe her story."