Justin Timberlake confronted dancer and choreographer Wade Robson over his “affair” with Britney Spears — while she was hosting “Saturday Night Live,” sources told Page Six.

The *NSYNC singer joined the “Toxic” superstar at the NBC show’s famed 30 Rock studios in Manhattan back on Feb. 2, 2002, and proudly introduced his then-girlfriend.

But just days before, Timberlake had found a lengthy break-up note she had written to Robson, sources said.

One former production source told Page Six, “Britney was pulling double duty as a musical guest and host [on ‘SNL’]. Justin had found a letter which made it clear that the affair had been going on for months and that she and Wade had been sleeping together.

“He had been trying to get ahold of Wade and finally got him on the phone as Britney was in the middle of ‘SNL.’

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Justin Timberlake spoke to Wade Robson about the dancer’s relationship with Britney Spears — as she was hosting “Saturday Night Live,” sources tell Page Six.NBCUniversal via Getty Images

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Britney Spears on stage with Justin Timberlake during her “SNL” monologue on Feb. 2, 2002.NBCUniversal via Getty Images

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Spears called Timberlake on stage as cast member Chris Kattan pretended to be her.NBCUniversal via Getty Images
“If you watch closely, you will see that he did not join Britney on stage at the end of the show when she thanked him.”

After the show ended, we’re told Spears, then 20, and Timberlake, 21 at the time, spent 40 minutes huddled in her dressing room before heading to the after-party they were hosting at Serafina. Their three-year romance ended just a month later.

In her new memoir, “The Woman in Me,” Spears confessed that she had cheated on Timberlake with Robson — after discovering her start boyfriend had cheated on her — and wrote they only kissed.

A rep for Spears had no comment on this.

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Although he was not on stage at the end of the live show, Timberlake was part of the group finale in rehearsal.NBCUniversal via Getty Images
“We were out one night and we went to a Spanish bar. We danced and danced. I made out with him that night,” the singer wrote of Robson.

Last week, singer-songwriter Annet Artani — who helped write the song “Everytime” with Spears in 2003 — told TMZ that Timberlake found a 14-page break-up letter from Spears to Robson, hinting that the affair was more serious than a kiss.

Timberlake, now married to Jessica Biel, joined Spears on stage at “SNL” back in 2002 as part of a joke with cast member Chris Kattan who was claiming that he was, in fact, Spears.

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Timberlake and Spears attended the “SNL” afterparty at Serafina.James Devaney/Big Pictures USA
“I know how to settle this, Justin, can you come out here for a second?” Spears called out.

Timberlake walked on stage to screams from fans, telling Spears, “Listen I just want to say I had a really great time last night.”

Follow Page Six’s coverage of ‘The Woman in Me’

“Justin, that was not me,” Spears replied.

“Kattan, you gotta stop doing that man!” Timberlake yelled, before introducing his girlfriend by saying, “Britney Spears is here!”

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Spears confessed in her memoir that she cheated on Timberlake with choreographer Wade Robson (above).WireImage
He then joked, “Baby, are you sure it wasn’t you?”

Spears and Timberlake, who were co-stars on “Mickey Mouse Club” as kids, began dating in 1999 before he broke up with the pop singer in March 2002 with a two-word text. As Page Six recently revealed, the message read, “It’s over.”

In her bombshell book, Spears also revealed that she had an abortion while with Timberlake after he told her he wasn’t ready for fatherhood.