Walker reveals struggles with mental disorder in just-released book

In the just-released book "Breaking Free," former NFL running back Herschel Walker delves into his excruciating struggles with dissociative identity disorder, saying he tried to manage a dozen alternate personalities and that the condition nearly drove him to suicide.

In a "Nightline" interview that will air Monday on ABC, the 46-year-old Walker said he has been in treatment for eight years and believes the disorder is under control, adding that writing the book was therapeutic for him.

"I've totally changed from back then to where I am today," he said. Details of the interview appear in a story on ABCNews.com. It is not clear at what point in his life Walker believes he had the disorder.

Following a Heisman Trophy-winning career at the University of Georgia, Walker spent three seasons in the USFL and then played 12 years in the NFL with the Minnesota Vikings, Dallas Cowboys and New York Giants. He also was a member of the 1992 U.S. Olympic bobsled team, with an array of other interests that included ballet and law enforcement.

After his retirement from football in 1997, Walker said the disorder began to overwhelm him. At one point, while sitting in his kitchen, he said he played Russian roulette with a loaded pistol.

"To challenge death like I was doing, you start saying, there's a problem here," Walker told ABC News correspondent Bob Woodruff.

DID, formerly known as multiple personality disorder, is described as a relatively rare mental condition where a person has two or more distinct personalities. The disorder has been dismissed by some in the medical field.

"Nightline" interviewed Walker's therapist, Jerry Mungadze, who said he met Walker's alternate personalities, or "alters," during their sessions.

"They will come out and say, I am so-and-so. I'm here to tell you Herschel is not doing too good," Mungadze said. " … When he finishes, it would just disappear back in him, and Herschel comes out."

Walker and his ex-wife, Cindy Grossman, were married for 16 years before she knew about his illness, she said.

"Well, now it makes perfect sense, because each personality has a different interest," Grossman told "Nightline." "This one has an interest in ballet, this one has an interest in the Marines, this one had an interest [in the] FBI, this one had an interest in sports.

"There was also a very sweet, lovable [personality]. That's the one he told me I married. He told me I didn't marry Herschel," said Grossman, who later in the interview recalled a conversation with Walker, "and the next thing I knew, he just kind of raged and he got a gun and put it to my temple."

When the topic of the book was revealed in January, Walker's father -- as well as a former teammate and Vince Dooley, Walker's coach at Georgia -- met the revelation with shock.

"I know him better than anybody 'cause I raised him," Willis Walker Sr. told the Atlanta Journal-Constitution at the time. "This is my first knowing about that."

Walker said he hoped "Breaking Free" will help change the public's image of DID and help others afflicted with the disorder.

"DID is not 'Sybil' or 'Three Faces of Eve.' DID is just an illness that people are dealing with," he said. In the book, he wrote, "I feel the greatest achievement of my life will be to tell the world my truth."