CLINT EASTWOOD’s sensational $375 million divorce battle is officially on – and it’s already turned ugly with allegations that the 83-year-old “Dirty Harry” star cheated with TWO women!

His furious wife Dina, 48, socked him with divorce papers on Oct. 22 to end their 17-year marriage and lay claim to a huge share of his fabulous fortune.

“She’ll get a bundle of money,” predicted celebrity divorce at­torney Raoul Felder. “This divorce could cost Clint hundreds of millions!”

In a blockbuster exclusive, The ENQUIRER can reveal what pushed Dina over the edge – and why she’s pre­pared to name both women in what promises to be one of the most explosive Hollywood divorces ever.

The first woman in Dina’s cross hairs is Eastwood’s Aussie girl­friend, blonde divorcee Erica Tomlinson-Fisher, 42 – the ex-wife of Dina’s high school boyfriend Scott Fisher.

And The ENQUIRER learned exclusively that her second target is another at­tractive blonde divorcee with whom Clint allegedly had a “Viagra hookup.”

In divorce papers filed in Mon­terey County Superior Court, former reality show star Dina is asking for physical custody of the couple’s only child together, daughter Morgan, 16.

Determined Dina also wants the Oscar winner to pay alimony and her attorney fees.

The ENQUIRER broke news of their split in May, and it was con­firmed in late August. Dina filed for legal separation on Sept. 9 but with­drew the papers just two days later.

“Dina was still holding out hope that Clint would dump Erica and come to his senses,” explained an insider.

But everything changed when Dina learned that Clint was moving Erica into their $20 mil­lion ranch estate in Carmel, Calif., which Dina had been per­sonally decorating over the past five years. “Dina really thought the two of them would spend the rest of their lives there together,” said the source.

“But when she heard of Clint’s plans to move Erica in, Dina felt it was a slap in the face – and it pushed her over the edge to file.”

Even though Dina is said to have a prenuptial agreement with Eastwood, divorce attorney Felder, who is closely follow­ing the case, explained that besides alimony: “What’s also in the pot is everything (he’s earned) between when they got married and what he has now.”

The couple is said to be worth a staggering $375 million.

To make matters worse for the Hollywood icon, he’s been romantically linked to a 49-year-old blonde he met at the Mission Ranch hotel he owns in Carmel, Calif.

According to the source, Dina’s friends believe that Eastwood’s “Viagra hookup” took place last spring.

The ENQUIRER confronted the woman – whose name we are withholding – about the purported affair.

Although she admitted she knows Clint, she snapped: “I have never had sex with him.”

But multiple insiders identi­fied her as one of Clint’s lovers. And the source confided: “If the divorce gets ugly, Dina’s prepared to name both women in court and see where the chips fall.”