Posted by Sabrina B. @gametimegirl

They called him Sweetness, but Chicago Bears great Walter Payton had a dark side, according to a biography to be released Oct. 4.

An excerpt of “Sweetness: The Enigmatic Life of Walter Payton,” by Jeff Pearlman will appear in the Oct. 3 issue of Sports Illustrated and describes the Hall of Famer as suicidal, abusing pain medication and dealing with a crumbling family situation.

Payton, who retired as the then-all-time leading rusher in NFL history after the 1987 season, was depressed and suicidal in the mid-1990s. Pearlman cites a letter to a friend in which Payton said he imagined himself killing those around him and then turning a gun on himself.

“Walter would call me all the time saying he was about to kill himself, he was tired,” Payton’s longtime agent Bud Holmes said, according to “He was angry. Nobody loved him. He wanted to be dead.”

Payton’s executive assistant, Ginny Quirk, echoed those sentiments.

“He would call and say, ‘you won’t see me when you get to the office tomorrow,’ ” she said. ” ‘Enjoy life without me.’ ”

Payton died of a rare liver disease and bile duct cancer in November 1999.

According to the book, Payton used pain pills and liquids to deal with injuries during his playing days and the practice continued after he retired. Sources told Pearlman that Payton took a cocktail of Tylenol and vicodin and kept tanks of nitrous oxide in his garage.

“Walter was pounding his body with medication,” Holmes said. “I wish I knew how bad it was, but at the time I really didn’t.”

According to the book, in 1988 Payton visited dentist offices complaining of tooth pain. He secured several prescriptions for morphine but raised red flags with at least one pharmacist, who called police. Payton was visited by officers but received only a warning.

Even seemingly great times in Payton’s life were filled with confusion, according to the book.

Payton had been living apart from his wife Connie since his retirement but hadn’t gone public because of his desire to protect his children and his image. He had been seeing a woman for five years when he was inducted into the Pro Football Hall of Fame in 1993, and both women showed up for the ceremonies.

“The introduction into the Pro Football Hall of Fame is supposed to be the greatest moment in his life,” said Quirk, who was charged with keeping the women apart. “And in truth, it was probably the worst. … Four full days, and Lita (not the real name of Payton’s mistress) and Connie were like two ships passing in the night. If Connie was scheduled to come late, I’d make sure Lita was there early. If Connie was there early, Lita would be there late. I can’t describe the horror of that trip.”

Nonetheless, the women did end up meeting.

“I introduced the two of them, and they sat and talked for a quite a while,” Holmes said, according to the excerpt. “They were friendly, chatty. There was no hair pulling. It was very civil.”

Connie had asked for the meeting, and according to Holmes, told Lita: “You can have him. He doesn’t want me or the children.”

Despite stories of depression and personal chaos, the book does recount Payton’s courageous side. Knowing he was going to die, Payton spent his final months hosting former Bears.

“I never heard him say, ‘Why me?’ ” fellow Hall of Famer Mike Singletary said, according to the book. “I know I would have been saying, ‘Why me? Why me? There are other guys out there killing people — why me?’ I never heard Walter say that.”

Former Bears offensive lineman Jimbo Covert also marveled at Payton’s grace under dire circumstances.

“I was there with about 30 other guys,” he said. “Walter took time to go around to everybody personally and grab him and say, ‘What are you doing?’ — just getting the down low on how you’d been. Can you imagine how strong a person he had to have been to do that? He knew he was going to die.”