In December of 1963, a little over one month after the assassination of President John F. Kennedy, 31-year-old Secret Service agent Clint Hill walked into the ocean, planning to end his life.

The agent who risked his life on Nov. 22, 1963, in an attempt to protect the president and first lady — and whose courage is forever memorialized in the Zapruder film — was consumed with feelings of failure.

Now 90 years old, Hill shares what happened that night in his new memoir, My Travels with Mrs. Kennedy. The book, coauthored with his wife, Lisa McCubbin Hill, is an emotional follow-up to their 2012 bestseller, Mrs. Kennedy and Me.

On Dec. 29, 1963, Hill, who had been assigned to lead Jacqueline Kennedy’s detail, was in Palm Beach, Florida, to accompany her and her two young children, Caroline and John, to visit the extended Kennedy family as they always had.

That night, he writes, “Guilt and anguish consumed me. All I could think about was Dallas. I was running as fast as I could, my arm reaching for the handholds on the trunk but it was like my legs were in quicksand. Mrs. Kennedy climbing out of the back seat, her terrified eyes looking but not seeing me, like I wasn’t there.”

He walked out out towards the ocean and entered the water, fully clothed. “Tears streamed down my cheeks, and as the cold water enveloped my legs, and then my chest, and up to my shoulders, the tears turned to sobs,” he writes. “I wanted the water to swallow me up.”

Over the roar of the ocean, he heard someone call his name. The next thing he knew, a Palm Beach police officer was dragging him out of the ocean.

Nearly 60 years after the assassination, Hill has never before revealed what happened that night. “Somehow, there is a sense of freedom in no longer keeping that darkness to myself,” he writes. “People will judge me, I’m sure. But no one — no one — has ever walked in my shoes.”

The memoir, out October 25, is Hill’s most personal book yet as he shares behind the scenes stories of his four years protecting the first lady.

“A lot of things happened in 1964,” he says. “It was the time when everything changed. Mrs. Kennedy had lost all the things associated with the Presidency and the children no longer had a father.”

That year, Hill stayed by Jackie’s side as she left Washington, D.C. and moved to Manhattan to begin a new life. He was then reassigned to the presidential detail protecting Lyndon B. Johnson. As he writes, “My job and my allegiance was to the US Secret Service, not to an individual.”

In the book, which also features 200 rare photos, he shares intimate memories of his time with the woman he still calls “Mrs. Kennedy,” many from their global travels where he got to see a side of her that few ever did.

And he remains steadfast in his loyalty. To this day, despite having risked his life to save the president, he writes, “For me there is no pride in what I did that day. While others may find my actions heroic, I consider them inadequate.”

Writing about the night in December 1963 was cathartic, says Hill, who hopes by sharing his story, he can also help others.

“I was going through what is now called PTSD,” he says. “I urge anyone who is suffering from PTSD, to find someone they trust so they can talk about it, so they know they are not alone.”

Original Article