Details of the book, including allegations of infidelity and Payton's thoughts about suicide, emerged last week. Author Jeff Pearlman says that those revelations are only one part of a book he called "definitive."
"When you have a five-page excerpt from a magazine that deals with one small segment of a person's life, and people haven't seen the 460-page book, I can understand it, obviously," said Pearlman.
Pearlman said he interviewed nearly 700 people for the book and did "insane amounts of reporting" on Payton.
"When I started working on this book... I told everyone I was interviewing I was doing a definitive biography," said Pearlman. "It doesn't mean it is a love letter; it doesn't mean it's a hate letter - definitive."
Among the details already released about the biography are claims of alleged drug use, saying Payton was hooked on painkillers.
In an exclusive interview with ABC7's Cheryl Burton, Payton's widow Connie flatly denied this.
"He didn't act like a person that was on medication or drugs," said Connie Payton. "He didn't slur words, and he didn't act crazy, and, you know, like he might have been a little bit out of it."
The new biography also reports that Payton was distraught prior to his induction into the Pro Football Hall of Fame over the fact that Connie and his girlfriend could - and in fact, did - meet.
The book reads: "They were friendly, chatty. There was no hair pulling. It was very civil." At one point Connie looked the mistress in the eyes and said, bluntly, "You can have him. He doesn't want me or the children."
"Some of what was said really did not happen, the only truth to that whole thing was that there was a lady there that Walter was involved with," Connie Payton told ABC7. "But at that point too, the reality of it is, Walter and I had not even been together, we had been separated for a long time."
Payton said she found out about a son Walter had out of wedlock after Walter's death.
Pearlman said he felt Payton's worries over the Hall of Fame induction were important enough to merit inclusion in the book.
"When you find out... that on the biggest occasion of a football player's life, his Hall of Fame induction, that for four days, he is freaking out, nervous as anything, because he is worried about his wife and his girlfriend meeting, I sort of think that is a significant detail from a person's life," said Pearlman. "When you write a definitive biography of somebody, it doesn't mean that everything is going to be easy to read or sometimes easily digestible. It is what it is."
Connie Payton did confirm one of the most jarring assertions in the book: that Payton struggled with suicidal thoughts.
"There were times that he said that he wanted to take his life, that he was unhappy and he wanted to take his life," Connie said. "During those times Cheryl, I truly didn't understand it because I would look at Walter, I looked at him and said, you are healthy, you've had a wonderful career, you've got money in the bank, really you are an accomplished person, why, why are you sad? Why are you depressed, why do you have these problems?"
Payton flatly denies the book's charge that in the height of his depression, Walter threatened to kill people around him before killing himself. She says he was seeing a therapist to help him cope with his depression.
Pearlman said he was "thrilled" to hear that many respected Chicago sportswriters had rallied to his defense, arguing that the excerpts include the most salacious details and the book presented a fair picture of Payton.
"[The controversy] sort of hurts me, because I put so much time and energy into this book, and I love Walter Payton," said Pearlman. "He was a good man with flaws, and all of us have flaws, and I really do think if people read the entire book and not merely a five-page excerpt from a segment of his life, they will get a very full picture of who he was as a human being."