One Manhattan psychiatrist, who reportedly has treated Courtney Love and Gwyneth Paltrow at his Murray Hill office, is all about helping — himself, that is.

Dr. Isaac Herschkopf used his influence to gain control of one patient’s bank account and hijack his Hamptons home and even talked patients into writing his family into their wills, according to the new podcast “The Shrink Next Door.”

“I felt like I was in a cult,” longtime patient Marty Markowitz, 77, told The Post. “He took over my life very quickly . . . It was one ethical violation after another.” (He is not related to the former Brooklyn borough president of the same name.)

Markowitz, the millionaire CEO of a fabric company, first saw “Ike,” as Herschkopf is known, in 1981. About two years into their thrice-weekly sessions, Markowitz came to believe his only sister was after his money. He claims that he was convinced of this by Ike, now 69.

“He had me write, and notarize, a letter to my sister, saying ‘Never call me again,’ ” Markowitz said, recalling how the doctor handed him scissors with instructions to cut his sister out of family photos.

Markowitz alleged on the podcast that, in 1984, Ike persuaded him to create the philanthropic Yaron Foundation and draft a new will leaving his eight-figure fortune to the foundation — which, other than Markowitz, only Ike and his wife, Becky, had access to as officers.

A year later, in 1985, Ike became a joint signatory on Markowitz’s $2.5 million Swiss bank account, Markowitz claimed.

He also alleged that the doctor “insist[ed]” he amend his will to leave his Hamptons estate to Becky.

“Becky loves the Southampton property, so I think it’s only right you leave the property to her,” Ike allegedly told Markowitz.

The Herschkopfs loved the home so much they allegedly installed a welcome mat with their name on it, hung a “Becky’s Kitchen” sign, blanketed the walls with photos of their family and, with Markowitz’s permission, had the home phone listed in the White Pages under the doctor’s pseudonym Isaac Stevens. According to Markowitz, the couple also took over the master suite while he slept in a guest room.

“People thought I was the caretaker,” Markowitz said of guests at the parties Ike threw at the property.

“Ike was like a celebrity. To be invited to Ike’s party meant you were in the inner circle,” a patient called Judith said on the podcast, which is hosted by Bloomberg Opinion columnist Joe Nocera.

“The more in crisis you are, the more vulnerable you are — Ike likes you that way”

At one of the bashes, she became fast friends with a fellow patient. When the friend fell out with Ike, “he had me write a letter that he basically dictated, basically ending [my] friendship [with the woman], which was a great loss,” Judith said on the podcast. “It was her or him.”

Judith also claimed that the doctor urged her to stop speaking to her mother and even convinced her not to attend the woman’s funeral.

“The more in crisis you are, the more vulnerable you are — Ike likes you that way,” Emily, another patient, said on the podcast.

They carried on therapeutic sessions for 17 years, often at restaurants including Le Cirque, Four Seasons and Daniel, with Emily footing the bills, in addition to Ike’s fee, she claimed.

Emily alleged that Ike convinced her to re-draw her will so that a “substantial” amount of the wealthy divorcée’s money would go to the doctor’s three daughters.

Ike was known for chasing not just the rich, but the famous.

“He was a celebrity whore,” Markowitz told The Post. He alleged that Ike once summoned him to receive a fax from patient Courtney Love in 2003. “I read the letter and photocopied it,” he admitted. “She was pouring her guts out [about her custody battle for daughter Frances].

“This was an epic violation.”

(Ike Herschkopf told The Post he can’t comment on any patients.)

In 2010, Markowitz had a hernia operation and Ike never checked in.

“He knew I had no one else,” said Markowitz, who changed his will immediately. “That was the last straw.” (Emily and Judith have also severed ties with Ike.)

After reuniting with his sister and reclaiming his home, Markowitz eventually filed a complaint with the New York State Department of Health, which is currently investigating the doctor.

Markowitz, who claimed he spent some $3 million seeing Ike over three decades, said he still lives with the pain inflicted during those years.

“He said I’m not lovable,” Markowitz said of Ike. “He was all about power and greed.

“Occasionally I’ll get a flashback of him, but I’m so happy with my life now. He’s not in my ear.”