Rock married Compton-Rock in 1996 and filed for divorce in 2014.
Their divorce was finalized last year.
The Rolling Stones piece describes how Rock admitted "I was a piece of s***" during his marriage to Compton-Rock, revealing that he cheated with three women: "one famous, one semi-famous, and one a member of the retail class."
A source told Page Six: "He was cheating on his wife with Kerry when they were filming [I Think I Love My Wife] about him, ironically, having fantasies of cheating on his wife.
"That went on for a while, for like six months, and she found out. There's no gray area."
The alleged affair took place in 2007, the same year Washington broke off her three-year-engagement to actor David Moscow.
The Scandal star has been married to NFL player Nnamdi Asomugha since 2013, with whom she shares a three-year-old daughter and a six-month-old son.
The New York Daily News previously reported that Washington began dating her husband when she starred in the Broadway play Race, which premiered in 2009.
A separate source told Page Six that while Rock's marriage was rocky, the "cheating admission" was just part of his routine.
"I take it as a joke when he says he cheated with a famous person. He even says he cheated with a member of Destiny's Child, but not Beyoncé," they said.
"He was friends with Kerry around that time. They did the movie together. He was also separated from Malaak around that time. They were off-and-on a lot during their marriage. It was a rocky situation."
Rock is currently in a relationship with 33-year-old actress Megalyn Echikunwoke.
