FKA Twigs has reportedly told Kristen Stewart to “shut the f**k up” and stop talking about Robert Pattinson.

The British singer has been dating the former Twilight actor since September last year. And following comments his ex-girlfriend made about a sex scene they had to film for the vampire franchise, the 27-year-old has reportedly issued an ultimatum.

“She sent a message to Kristen to ‘shut the f**k up’ about Robert because she lost the right to speak about him in public ‘the moment she got into that car with Rupert Sanders,’” a source told the American edition of OK! Magazine. “It was pretty brutal.”

Robert dated co-star Kristen from 2008 until 2012. They split after US Weekly published photographs of the 25-year-old embracing her married Snow White and the Huntsman director Rupert Sanders.

During a recent interview with the British edition of Harper’s Bazaar, Kristen referred to a Twilight sex scene with Robert as “agony” and “grotesquely uncomfortable”.

The insider told OK! that the 29-year-old has since opened up to FKA about “that whole nightmare” and how he wanted to “quit acting forever”.

The couple are reportedly engaged to be married, and the source added that FKA is “Rob’s fiercest defender”, particularly when it comes to his ex and the media circus that surrounds her.

And it seems that the Still Alice star has taken notice of the singers warning.

“It will be a very long time before Kristen talks about Rob again in public,” the source said.