Now that is Brat.

Charli

The singer, 32, used Stewart, 83, and falsely claimed Peyser was dead in her Netflix documentary, and Peyser’s subsequent “I’m living bitch!” clap back, as an example of what ‘brat’ is.

“Honestly, it’s just an attitude,” Charli said. “It’s an atmosphere. For example, Martha Stewart’s new documentary: When Martha gets angry about an old magazine article and says she’s glad the journalist who wrote it is dead, is a brat.”

“And last Friday, when that exact journalist responded and said, ‘Hey, I’m still alive, bitch,’ it’s extremely brat,” Charli added.

The “Apple” singer then declared that “anyone can be Brat,” as she was joined on stage by “SNL” alumnus Kyle Mooney.

Peyser told The Post exclusively: “Word to Mistress Martha: I am still alive. Bitch. I’m floored at being called “extremely ‘snot’ on SNL.” And glad Martha Stewart is just a “brat.” However, I’m still a little scared that I lived rent-free in Martha’s head for so long.

In the documentary “Martha,” Stewart talked about the “New York Post lady” who wrote “terrible” things about her during her 2004 trial for insider trading. The famous housewife served five months in prison for her crimes.

“But thank God she’s dead now,” Stewart said of Peyser, without ever mentioning her by name.

“And no one has to put up with the crap she was writing all the time,” she added.

But Peyser — who covered Stewart’s six-week trial almost daily from the Manhattan courtroom for The Post — responded to Stewart: “I’m still alive, bitch.”

“The news of my death came as a shock. Should I be afraid to continue writing that ‘nonsense’?” the writer added in her November 7 column.

“Long after she and her insider-tipping stockbroker Peter Bacanovic were convicted of securities fraud and other crimes, and then lied about it to federal investigators, her thoughts are not with her family, her pink-slipped employees, her mini-menagerie of animals, or even her own miserable self. She turned her anger on me,” Peyser wrote.

She also said, “Martha thinks I’m ‘dead.'” But instead of feeling angry or concerned that Martha has offended me, or seeking an emergency order of protection, I feel overwhelmingly sad when confronted with Martha’s bitterness.”

Stewart responded to Peyser’s column while speaking at the Philadelphia Conference for Women event, telling the audience, “She wrote this very scathing article today in the New York Post — my favorite newspaper.”

After reading Peyser’s headline, which caused audible gasps from the audience, Stewart added, “So that will probably lead to more people watching my documentary.”

The former talk show host also emphasized her innocence, calling her securities fraud crimes “a crime I did not commit.”