Jimmy Buffett's Kids Grilled About Mom's Alleged Ketamine Use In $275M Legal War

The legal war over Jimmy Buffett's estate is turning ugly … with the late singer's children fielding questions about their mom's alleged drug use ... TMZ has learned.

According to court docs, obtained by TMZ, Jimmy's son Cameron and daughter Sarah Delaney Buffett, were asked questions about their mom, Jane Buffett, during discovery ... and they were badgered specifically about ketamine and marijuana.

The questions were raised by Jimmy's former financial advisor, Richard Mozenter, as part of the legal battle over control of Jimmy's estate, which is reportedly worth an estimated $275 million.