Britney Spears, Justin Timberlake love felt long term, says sister Jamie Lynn Spears

Britney Spears' sister Jamie Lynn Spears is touching upon her sister's heartbreaking breakup from Justin Timberlake.

Speaking in a recent interview obtained by PEOPLE, the younger sister shares how Britney's condition makes her cry to date.

"I think everyone thought it was forever," said the 30-year-old. "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," said Jamie Lynn, who was only a teenager when the breakup happened.

She however kept mum as to why Britney broke up with Timberlake. Jamie Lynn then shared how sister wrote Cry Me a River for her ex-boyfriend after breakup.

"I thought how heartbreaking it must have been for my sister when Cry Me a River came out,"she said. "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."

She continued, "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."