She stole his heart, but it’s his kidney that he wants back.

A Long Island surgeon who dumped his wife after she allegedly had a steamy affair wants her to give back the kidney he lovingly gave her, or fork over the $1.5 million he claims the organ is worth.

“I saved her life and then, to be betrayed like this, is unfathomable. It’s incomprehensible,” said Dr. Richard Batista, 49.

“I feel humbled and betrayed and disregarded. This divorce is killing me.”

Batista, a vascular surgeon at Nassau University Medical Center, claimed his wife left him after getting physical with her physical therapist.

He said the couple married on Aug. 31, 1990, in “a very nice, lavish wedding,” but two years later, the relationship began a “slow downward trend.”

Since he filed for divorce in 2005, he said, she has made it increasingly difficult for him see their three children.

“The main reason the doctor is doing this is because of how he’s been treated in this case,” said Dominic Barbara, Batista’s lawyer.

They are asking for the $1.5 million as part of the distribution of assets based on a medical expert’s estimated value of the kidney.

“In theory, we are asking for the return of the kidney,” Barbara said. “Of course, he wouldn’t really ask for that, but the value of it.”

Dawnell Batista, a physician’s assistant at Winthrop Hospital in Garden City, had her first kidney transplant as a baby, with her father as the donor, and a second one years later, from her brother. Her body rejected both kidneys.

Her husband then donated one of his healthy organs to her in June 2001.

“There’s no greater feeling on the planet” than to save a life, said the surgeon, who lives in Ronkonkoma.

But Dawnell’s new lease on life left her with a wandering eye, he claimed.

Within two years of the lifesaving transplant, he said, she suffered a knee injury during a karate class – then hopped into bed with her physical therapist.

Even worse, she flaunted her romance – once leaving her lover’s clothes in the family laundry, he claimed.

The physical therapist, David Cazalet, vehemently denied the accusation.

“We’re friends – we’ve never had an affair,” he insisted, calling Batista a “big monster.”

“I feel bad for her because he’s a wackadoo,” he said.

Dawnell Batista’s lawyer refused to comment.

“She’s a wonderful person,” said her mother, Cynthia Carroll.

A brother, who asked that his name not be used, said, “You expect the worst from a bad person.”

lorena.mongelli@nypost.com