In the aftermath of Britney Spears' heartfelt apology, she was surprised by the response she received from her ex-boyfriend Justin Timberlake.

The former NSYNC star wasted no time throwing shade at the "Baby One More Time" singer, despite her recent public admission of past mistakes and her sincere attempt to make amends for their tumultuous relationship from 1999 to 2002.

Britney Spears Humiliated

According to a source who spoke to OK magazine, Britney Spears felt deeply hurt by Justin Timberlake's unexpected response, which seemed like a cruel jab.

The source revealed that she had genuinely tried to mend their relationship by expressing her admiration for his latest song, "Sanctified," even going so far as to say she was in love with it.

However, Justin appeared indifferent to her gesture, leaving the mom-of-two feeling rejected once again.

An insider noted lingering anger from him toward her memoir, "The Woman in Me."

This memoir unveiled shocking truths through Britney's detailed account, where she disclosed having an abortion while in a relationship with Justin and also accused the "Can't Stop the Feeling" singer of infidelity on multiple occasions.

Justin Timberlake Heartless?

Britney Spears efforts to uplift Justin Timberlake by commending his latest music were met with rudeness and rejection, according to a source.

Despite facing such humiliation, Britney can take solace in staying true to her principles.

This recent apology from the "Toxic" singer, shared on Instagram on January 29th, caught her fans off guard as she expressed remorse for specific content in her book.

READ ALSO: Justin Timberlake, Jessica Biel In Desperate Bid to Save Marriage? New Details Emerge Amid Britney Spears Controversy

Expressing profound apologies to anyone she may have unintentionally offended, the "Womanizer" singer reflected on a recent event where she shared her admiration for Justin Timberlake's latest hit, "Selfish."

In a heartfelt caption accompanying a clip from Justin's appearance on Jimmy Fallon's talk show, she also couldn't help but express her amusement whenever she witnessed the comedic chemistry between Justin and Jimmy.

"If I offended any people I genuinely care about I am deeply sorry. I also wanted to say I am in love with Justin Timberlake's new song 'Selfish' . It is soo good and how come every time I see Justin and Jimmy together I laugh so hard ??? Ps' Sanctified' is wow too."

Tensions surrounding the situation on Justin's side were far from settled by Britney's apology.

Instead of expressing remorse, he seized the moment during his concert at Irving Plaza in New York City on Wednesday, January 31, to send a resounding message: "an apology to absolutely f------ nobody."

Right before Justin launched into his "Cry Me a River" performance, a surprising declaration left the audience in shock.

Many speculate that the lyrics of this 2002 hit reflect the end of his relationship with the "Mirror" singer, Britney.

Following his controversial statement, Britney felt compelled to rescind her previous apology. With a swift response on Instagram, she retracted the kind words she had previously expressed.

READ MORE: Britney Spears Revels in Rule-Breaking Glory Post-Liberation from Conservatorship: 'People Were Making Complaints'

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