A Westchester attorney and mother of three — who posted on social media that she was about to undergo assisted suicide in Switzerland because of a grueling custody battle — died overseas on May 27, documents obtained by The Post show.

Catherine Kassenoff, 54, died in the tiny town of Oristalstrasse, Switzerland, about an hour west of Zurich, records show.

Her cause of death was not revealed, “due to Swiss Medical Confidentiality Act,” according to the document.

An attorney who once worked for Gov. Hochul, Kassenoff — who had been diagnosed with terminal cancer — placed a suicide note on Facebook claiming she was choosing to die by assisted suicide in part because of “a prolonged separation from my children.”

“It is with a profound heartbreak … that I am writing my last post ever. Today, I will be ending my own life … In the last four years of my life I have woken up every day to a nightmare like no other,” she wrote in May.

“I cannot survive this torment and the grief that comes from such a prolonged separation from my children … The court system did this to me … It is a predatory system that functions in darkness…”

A Westchester family court had cut her off from contact with her three daughters, ages 9, 12, and 13 amid a brutal legal battle with her ex, Allan Kassenoff, who at one point wrote to her that, “you must be really proud of yourself for financially decimating me and the children.”

Confirmation of Kassenoff’s death was first reported Friday by a legal news site, The
Frank Report, citing a letter sent from Kassenoff’s attorney Harold Burke to a federal
judge.

Records show Catherine Kassenoff filed at least one lawsuit and continued to seek legal action against Allan Kassenoff in federal court. 

In the letter dated July 6, Burke wrote that he had been notified by the US Consulate of Kassenoff’s death the month before.

Her apparent death was also confirmed in a Consular Report of Death Abroad, issued by the US State Department and seen by The Post.

A CRDA is typically issued by a US embassy or consulate based on a foreign death certificate or after findings of death by a local competent authority when a US citizen dies abroad, according to the State Department’s website.

Her body was cremated, and the ashes sent to the executor of her estate, Wayne Baker, the CRDA shows.

Burke did not return a message seeking comment.

Baker declined comment.

As news of her supposed suicide spread, Kassenoff became known AS a symbol for the need for
family court reform.

Her story went viral on TikTok garnering millions of views.

As the story spread, allegations of abuse surfaced against Alan Kassenoff, resigned, his firm, Greenberg Traurig, said in statements at the time.

Allan Kassenoff will retain sole custody of his daughters following the death of Catherine, who was known as a fearless federal prosecutor and breast cancer survivor.