The already-sour relationship between ex-Pink Floyd bandmates Roger Waters and David Gilmour seemed to take an irreparable turn on Monday.

Gilmour’s wife, novelist and lyricist Polly Samson, fired off a tweet accusing Waters of being “antisemitic to your rotten core” and called him “a Putin apologist and a lying, thieving, hypocritical, tax-avoiding, lip-synching, misogynistic, sick-with-envy, megalomaniac.”

It’s not clear what specifically prompted the message, but it may have been an interview Waters did with Germany’s Berliner Zeitung newspaper in which he said he stood by comments comparing modern Israel to Nazi Germany for its treatment of Palestinians, accused the Israelis of genocide and defended his boycott of the nation.

Waters, who quit Pink Floyd nearly 40 years ago, also wrote on his website that the “Israel lobby” is trying to silence him via a “despicable smear campaign” while he insisted he’s not antisemitic.

He also posted another message in response to Samson, calling her comments “incendiary and wildly inaccurate,” and implied he was considering legal action.

Gilmour, who posts only very occasionally on social media, hit back later in the day with a tweet that said his wife was delivering just the basic facts:

Waters is a supporter of the Boycott, Divestment and Sanctions movement that targets Israel over the treatment of Palestinians. Some argue his words and actions have crossed the line into antisemitism, which Waters has angrily denied.

Waters has also defended Russian President Vladimir Putin, criticized Ukrainian President Volodymyr Zelenskyy and called U.S. President Joe Biden a war criminal over the war in Ukraine.

His former bandmates, on the other hand, reunited last year to release a single under the Pink Floyd name in support of Ukraine. “Hey, Hey, Rise Up!” features vocals by Andriy Khlyvnyuk of the Ukrainian band BoomBox as well as a Ukrainian choir.

In his new interview, Waters trashed the band as “really, really sad” and “lacking in humanity” over the move.

Waters has had a famously contentious relationship with the other members of Pink Floyd even when he was in the band. He ultimately quit the group after the release of 1983′s “The Final Cut,” then went to court to stop the other members from using the band’s name.

It was ultimately settled out of court, and the band carried on without him.

There’s been little love between them since, but Waters and Gilmour have shared the stage on a handful of occasions, most notably a one-shot Pink Floyd reunion in 2005 for Live 8, a global event to help fight poverty.

Waters and Gilmour were joined there by Nick Mason on drums and Richard Wright on keyboards, both founding members of the Floyd.

Wright died three years later.

Waters just wrapped up a solo tour of the United States and hits Europe in spring. Gilmour did some livestreams from home during the pandemic but hasn’t toured since 2016, when he traveled as a solo act. Mason has been touring with his own band, Nick Mason’s Saucerful of Secrets, which focuses on Pink Floyd’s earliest songs.