Ted Kennedy’s accomplishments were always measured against Chappaquiddick—the night he drove a car off a bridge into a pond, swam to shore, failed to report the accident, and left behind a young campaign worker who drowned.

Now in his memoirs to be published this month, Kennedy wrote that he made terrible decisions the night Mary Jo Kopechne died.

The 532-page book—to be published Sept. 14 by Twelve, a division of the Hachette book group—was obtained early by The New York Times and the New York Daily News.

“In it, Kennedy said his actions on Chappaquiddick Island on July 18, 1969, were “inexcusable,” the Associated Press reported. “He said he was afraid and “made terrible decisions” and had to live with the guilt for more than four decades.”

“He wrote that he had no romantic relationship with Kopechne, and he hardly knew her. He said they were both getting emotional about his brother’s death and decided to leave the party that was hosted by Robert Kennedy’s former staffers.”

Kennedy was then 37. He pleaded guilty to leaving the scene of an accident. He received a suspended sentence and probation.

PHOTO: Members of the public signs the book of condolences for Sen. Edward Kennedy at the U.S. embassy in Dublin, Ireland, Friday. Kennedy was remembered as a flawed but passionate friend of Ireland who helped bring peace to the divided north and pride to Roman Catholics in the south. (AP Photo/Peter Morrison)