Los Angeles, California - Britney Spears' feud with Justin Timberlake reportedly bothered her more than anyone knew!

Per US Weekly, the 42-year-old pop star was trying to "move forward" from her issues with her famous ex until his latest dig towards her.

An insider dished that Britney was "annoyed" after Justin told an audience in New York that he wanted to "take this opportunity to apologize to absolutely f**king nobody" amid controversy stemming from her revelations about their ill-fated romance in her memoir.

The source explained that the Womanizer artist was hurt over the comment since the "turning point for her mental issues started when Justin broke up with her so many years ago."

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The tipster continued that Britney "thought they'd be together forever and have children."

"So when he broke up with her, it shook her world," the source claims, noting that "things shifted with her and she started having problems" after their split.

Britney didn't hold back on the pair's tumultuous relationship in her memoir, The Woman in Me, including the bombshell that the Gimme More singer had an excruciating at-home abortion.

"But when he made fun of her apology, it triggered her," the insider continued, adding, "Those close to her wish Justin was more of a stand-up guy and would have just moved on because what he did really hinders her recovery."

The exes' drama continues!