Jamie Lynn Spears opens up about her sister Britney Spears’ relationship with Justin Timberlake.

The star is set to appear on the “Call Her Daddy” podcast for a two-part episode, where they talk about her sister’s famous split from the boy band member.

“I think everyone thought it was forever,” Jamie said in a preview shared with People. “I was so sad, first off because my sister was so sad, but that, too, was the first time I saw [that] maybe I didn’t know everything about the relationship. Perhaps they were protecting me and obviously why would they talk to me about anything.”

Britney and Timberlake dated from 1998 to 2002, in their teens. Shortly after their break-up, the *NSYNC member released the track “Cry Me a River” which was widely theorized to be about their split.

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The music video featured a blonde woman acting opposite the star, and the lyrics seemed to imply an ex-girlfriend cheated on him.

“I thought how heartbreaking it must have been for my sister when ‘Cry Me a River’ came out,” said Jamie. “Don’t get me wrong, like, that’s a way to launch your solo career, right? That’s a way to do it, but I felt really sad. And my sister, she wrote that song ‘Everytime’ and she’s beyond brilliant with anything creative and she picked that song out on the piano and she wrote it and it still makes me cry, because I think about how heartbroken she was, because that was her song and that was his song.”

Timberlake eventually apologized for his treatment of Britney after the documentary “Framing Britney Spears” brought their relationship back into the public eye. In the documentary, they analyzed a 2002 clip where the singer admitted he had slept with Britney.

READ MORE: Britney Spears Calls Out Jamie Lynn In New Open Letter: ‘You Say You Love Me… Yet Your Loyalty Is Still With The People That Hurt Me’

When it comes to Jamie’s own relationship with her sister, the two have been feuding publicly over their relationship during the conservatorship and Jamie’s new book Things I Should Have Said.

In a preview that “Call Her Daddy” shared on Twitter for part two, they teased an exclusive text message.

“You have a text message that clears your name from your sister. Can you pull out your phone and read that recent text from Britney?” Host Alex Cooper asks.

The new episode of “Call Her Daddy” airs on Jan. 18 at midnight.