RICHARD HATCH triumphed on “Survivor” using his cunning, intelligence and charm — but now he’s involved in his most brutal battle ever as a former lover opens fire on him.

Glenn Boyanowski — who recently clashed with 40-year-old Hatch in a headline-making fight outside his home — says the handsome businessman is battling depression, has ballooned to 280 pounds, prowls the Internet for lovers and pumps himself up with Viagra.

But an irate Hatch fires back that his ex-lover Glenn is “not stable” and is acting out of jealousy.

In an exclusive interview, Glenn told The ENQUIRER that their brawl was far more vicious than reported — and that Richard even tried to strangle him.

But Hatch insists he merely pushed Glenn out of the way to keep him from barging into his house.

Glenn, 39, moved in with Richard in January and worked as “a nanny” for his son Christopher. In May he moved out — but continued to care for Richard’s 10-year-old son.

He says he and Richard also continued to get together on a social basis “but Richard had been putting personal ads on the Web and met another man.

“I still considered Richard my boyfriend and I decided to go over and talk to him about continuing my job with him.”

Glenn says as he walked up the steps, Richard — clad only in a towel — confronted him.

In a court document, obtained by The ENQUIRER, Hatch says Glenn was “angry and irrational and dangerous” and that he pushed Glenn away “to defend myself and my family.”

But Glenn insists the 6-foot-4 “Survivor” winner flew into a terrifying rage.

“He started yelling, ‘Get off my property!’ And he grabbed me by the neck and started to choke me.

“Then he punched me twice in the side of the head. He pulled me down by the neck and kneed me in the face.

“I loved him and he had told me he loved me. He promised we’d be together forever — right up until the time he grabbed me by the neck and started punching me.”

Richard Hatch once weighed as much as 360 pounds.

Hatch’s hoped-for showbiz career had been fizzling and he failed his tryout to host “The Weakest Link.”

What’s more, says Glenn, “Richard’s personal life is a mess and his self-image goes up and down with the size of his stomach.”

While the police report of the fight says Hatch weighs 230 pounds, Glenn says that’s way off. “He’s more like 280. He balloons up and down,” he told The ENQUIRER.

“He’s depressed and the biggest reason is his weight. He’s addicted to food. He eats out for lunch and dinner almost every day — and then he buys big bags of muffins and cookies that he’s always secretly eating. One day I found a huge bag of candy bars hidden in the closet.”

Glenn says Hatch considers himself a born-again Christian and no longer drinks or smokes — but he does give his sex life a boost with Viagra.

Following the ex-lovers’ nasty August 20 encounter, Hatch pleaded innocent to misdemeanor assault and a hearing was set for early September.

Meanwhile, Hatch obtained a court order to keep Glenn away from him.

Glenn blasts his ex-partner as a “control freak.” But, in fact, Richard is more worried now than he was before any tribal council. Hatch told authorities, “I am in fear of imminent physical harm from (Glenn) as a result of his irrationality . . .”

— Richard Gooding