Saying bye, bye, bye was tougher for Justin Timberlake than fans may think! The "Mirrors" singer, who stepped away from 'N Sync back in 2003 for a superstar solo career, revealed during an appearance on Oprah's Master Class premiere Sunday night that leaving his four bandmates behind was one of the "best slash worst" decisions he's ever made.

"I would wake up every morning feeling this more and more of an urge to step out on my own and try my own hand as a musician just by myself," Timberlake, 33, said of needing to break out.

"It was happening all around me: 'What are you doing? Why wouldn't you ride this out? You're the biggest group in the world. Why would you walk away from this?'" he recalled people telling him.

"It's one of the best slash worst things that I have ever done because it was bittersweet," he continued. "It was hard to say goodbye to that era, but I felt it changing. I felt music changing. And I felt myself changing."

Eleven(!) years after leaving the boy band, Timberlake reunited with JC Chasez, Joey Fatone, Lance Bass, and Chris Kirkpatrick for an unforgettable, nostalgia-packed performance at the 2013 MTV Video Music Awards last August in NYC. (They last performed at 2003's Grammy Awards.)

Timberlake's former bandmates were on hand to help celebrate his win for the Video Vanguard Award, and later partied together at Jay Z's VMAs after party at downtown Manhattan club PH-D. Although an insider told Us the band was "pushing" for more than just a minute out of his 15-minute solo set, all seemed well and tension-free when the men reunited once again at Kirkpatrick's wedding three months later.