WWW- The Liza Minnelli-David Gest court clash has gone from nasty to nuclear, with Minnelli accusing her estranged hubby of having tried to “poison” her, and Gest charging that his marriage to “Liza with a Z” had him scared that he was David with an STD.

According to papers filed in Manhattan Supreme Court, the four-times-married Minnelli, 60, claims that she was “living in fear” while she and the producer were together, afraid he was “trying to poison her with drugs.”

Gest, meanwhile, claims that the Oscar-winner – who he says repeatedly beat him – hid her sexually transmitted disease, herpes simplex, from him until well after they tied the knot. Gest said he never contracted any sexual disease.

“David was devastated when he found [this] out a year after they had been together and six months after they were married,” a source close to him said.

In the public court filing, Gest’s lawyer demands to know when and how Minnelli got infected – and says his 53-year-old client plans to make her medical condition an issue in their long-running divorce case, in which each is accusing the other of being “cruel and inhuman.”

If she had herpes before they got married in March 2002, the filing says, that would be fraud and their prenuptial agreement could be thrown out – which would enable Gest to go after the “Cabaret” star’s cash.

But Minnelli’s side is arguing that it was Gest who violated the prenup “by seeking to learn the circumstances of the infection that was disclosed to him during the relationship, after unprotected relations,” so she should be able to go after his money.

The case will be back in court Friday.

The former lovebirds have been trading outrageous charges since parting ways in July 2003.

Gest accused Minnelli of having beaten him so badly during alcohol-fueled rampages that he had to get 80 injections in his head every three weeks for a year to deal with the pain.

Minnelli accused Gest of being a master manipulator who made off with millions of dollars in her money.

In court papers stamped June 22, Gest lawyer Lawrence Omansky claimed that at her deposition, Minnelli denied ever hitting Gest. Yet, Omansky noted, her attorneys have been preparing a fallback “justification” defense based on concerns Gest was drugging her.

The filing said Gest had her “afraid for her life.”

The filing was short on details of how Gest was allegedly drugging Minnelli. Her lawyer could not be reached for comment.

But the filing did say Minnelli confided in a number of people about her concerns, including actress Mia Farrow, concert producer Ron Delsener and a rehab-center worker.

Lorraine Nadel, another Gest lawyer, said the drugging allegation is “ridiculous” and noted Minnelli had a slew of bodyguards and staffers who would have helped her at the time.