The oil heir famously enjoyed a fling with British actress Sienna in 2008, despite still being married to Rosetta, the mother of his four children, who he wed in 2000.
The cheating scandal led to a two-year separation between Balthazar and his fashion designer spouse, but they eventually reconciled and have since rekindled their romance.
Getty, now 41, admits the couple has long moved past the extramarital indiscretion, telling Britain's Evening Standard newspaper the affair is "ancient history" and feels like "another lifetime".
In a rare, candid chat, the former Brothers & Sisters star insists the incident has only made his marriage "stronger", admitting, "Without going down, you can't rise again."
Balthazar declined to discuss the issue further, but he previously heaped praise on his "understanding" wife for doing what's best for their kids.
"Here's the bottom line: It was a very challenging time for everybody involved," he told America's Harper's Bazaar magazine in 2010. "But I loved and missed my family too much not to make it work. Rosetta is understanding enough and spiritual enough to let us try."
Getty isn't the only one to face up to his past mistakes - in 2014, Sienna also came clean about her bad behaviour as she also touched on her other infamous fling with Daniel Craig, who she romanced in 2005 while she was dating Jude Law.
She told Britain's Esquire magazine, "I sabotaged things. I burnt a lot of bridges."
"On set, I was first to arrive, last to leave, best friends with the crew, totally professional, no d**king around," she added. "But when I wasn't at work, I wasn't behaving the way you should."
Confessing she is thankful to still be working in Hollywood, she continued, "I'm very lucky to have a second chance in that town... It was really bad. What was going on in my private life was not an easy thing to read about. People don't want to see films with people they don't approve of in them."
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