Foo Fighters frontman Dave Grohl recently feuded with former President Donald Trump, whom he has bashed in the past, over the allegedly unauthorized use of one of the rock band's songs at a campaign rally.

Trump may have the last laugh, however, after the supposed holier-than-thou rocker Grohl admitted this week to cheating on his wife and fathering a child out of wedlock, according to the Daily Mail.

The shocking admission sharply undermines the "family man" persona Grohl has embraced over the years and threatens to destroy his 21-year marriage to wife Jordyn Blum, with whom he shares three daughters.

Infidelity admitted

In Tuesday's surprise announcement on his Instagram account, Grohl wrote, "I've recently become the father of a new baby daughter, born outside of my marriage. I plan to be a loving and supportive parent to her."

"I love my wife and my children, and I am doing everything I can to regain their trust and earn their forgiveness," he added. "We're grateful for your consideration toward all the children involved, as we move forward together."

Grohl, 55, met Blum, 48, in 2001 when he was at the height of rock stardom and she was a former model and producer for MTV, and the couple dated for a couple of years before getting married.

Following their 2003 wedding, Grohl and Blum had three daughters -- Violet, Harper, and Ophelia -- and the man who once reveled in the licentious rocker lifestyle -- his first marriage to Jennifer Leigh Youngblood ended with divorce in 1997 after he cheated on her -- settled down and adopted the more reserved "family man" persona.

The Daily Mail noted that Grohl had become increasingly adamant about how important his family is to him in various interviews over the past decade.

Reportedly hired a divorce attorney

All of that for Grohl -- his marriage, his family, and his new persona -- are all at risk now as People magazine reported exclusively that the guitarist and lead singer hired a divorce attorney before making his public announcement about his infidelity.

That tidbit came from an unidentified source, the outlet noted, and a request for comment or confirmation to Grohl's representative went unanswered.

And in potentially related news, People observed that Grohl's eldest daughter, Violet, 18, with whom he has performed on stage in the past, deactivated her social media accounts, though it is unclear exactly when she decided to do so.

Feuding with Trump over unauthorized use of song

This apparent fall from grace for Grohl comes just a few weeks after he and his band picked a legal fight with former President Trump, whom Grohl has sharply criticized in the past, after Trump used one of their songs at a campaign rally without first requesting the band's permission -- though it is unclear if that express permission was even necessary.

At an Aug. 23 rally in Arizona, Trump's campaign played the Foo Fighters' 1997 hit "My Hero" to introduce Robert F. Kennedy Jr. to the crowd just hours after Kennedy effectively suspended his independent bid for the presidency and endorsed Trump's re-election effort.

In a statement to Billboard at the time, a spokesperson for the band said, "Foo Fighters were not asked permission, and if they were, they would not have granted it," to use the song. The spokesperson further threatened a lawsuit and that "appropriate actions are being taken" as well as that any potential royalties received for the use of the song would be donated to the Democratic campaign of Vice President Kamala Harris and Minnesota Gov. Tim Walz.