Therapist Dying of Cancer Leaves Viral Goodbye Message: 'I Was Completely Shocked,' Husband Says (Exclusive)

Sarah Mandel lived with transparency in "both the good and bad" and "let herself feel," her brother says

On June 1, New York City psychologist and author Sarah Mandel posted a video on social media that stunned even members of her own family.

In the message, Mandel, who was diagnosed with stage 4 breast cancer in 2017, announced her own death, just weeks away from her 43rd birthday.

"If you're reading these words right now, I have died," states a caption on the video, which featured a mix of personal videos and photos. "I wrote this message the week I was told I had weeks to months to live."

“Only a year ago, I never in a million years would have thought I would want my death announced on social media,” she continued writing in the captions.

But "life is unpredictable and full of surprises," she wrote, and she had discovered that the support she received from "old friends, new friends and strangers" helped her face even the "toughest days of this cancer ordeal."

"We all need our hands held sometimes," she wrote.

As the video came to a close, Mandel shared her love for her "beloved" husband and their daughters: "I'll write it here, and if I could, I'd write it everywhere. Sophie and Siena, I love you and I am so proud of you. I may be somewhere beyond our concepts of infinity. That's how much I love you."

Her husband, Derek Rodenhausen, tells PEOPLE in an interview that he saw the video after going on Instagram to check if anyone had posted about Mandel's death.

"I was completely shocked," he says. "She didn't tell anybody about that."

Although her older brother, Benjamin Mandel, had no idea it was coming either, he says the mom of two always saw the world "a little differently."

"There was a family story where we were taking a road trip and she saw this kind of bleak winter landscape with a crow on a tree, because everything was kind of gray and dark, and she said, 'That's beautiful,' " he recalls.

Afterwards, she went home and drew a multicolored and happy picture.

Sarah studied art at Bard College, where she met Rodenhausen, now 42, after studying abroad in Italy.

The two married in 2010 and then welcomed daughters. Sarah's eventual career shift to psychotherapy led her to get her post-baccalaureate degree at Columbia University and a psychology doctorate at Rutgers University.

Related: Woman Who Announced Own Death Organized Campaign to Pay Off Others' Medical Debt — and It's Raised Over $600K 

In 2017, while pregnant with Siena, Mandel, then 36, was diagnosed with stage IV breast cancer after feeling a lump in her breast.

"The thought was, 'This is probably just a clogged milk duct, so we'll watch it,' " her brother explains. But it didn't get better.

Right before her daughter's delivery, doctors ended up doing an ultrasound and a biopsy, and it turned out that she had cancer.

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After chemotherapy and radiation therapy, Sarah went on the drug Herceptin, which kept her cancer "at bay," according to her brother.

"She went back to having no evidence of disease, which was miraculous," her husband adds. "Then we had a couple good years where she was in pretty good health again."

Related: TikTok Star Maddy Baloy's Fiancé Held Her Hand as She Took Last Breath After Year with Terminal Cancer (Exclusive)

But by 2021, Sarah began to have headaches.

She went to Memorial Sloan Kettering Cancer Center, where MRI imaging showed the cancer was spreading into her brain.

"Then it was just a matter of trying to manage that, which involved multiple different types of medical therapy, radiation therapy again, and it kind of kept things quiet for a bit, but it did ultimately progress," Benjamin says.

Related: Father Diagnosed with Stage 4 Cancer Says Final Goodbye to Loved Ones: ‘It’s Gonna Be OK’

Sarah, who closed her practice in 2021 due to her illness, went on to publish Little Earthquakes: A Memoir in April 2023.

"As she started to write it, she started to weave in memories and parts of her own life, and it became a memoir ... but also has a self-help component of helping people know how to navigate their own traumas," her husband says.

While Sarah wasn't a "social media person," Rodenhausen says she began to use her accounts to document her life and treatment because "she still felt like she had things to give."

At the end of her life, according to her goodbye video, "she was thankfully very calm and comfortable in her final restful days. As throughout her life, she spent her final night surrounded by love. She was cuddled up with her girls, Siena and Sophie, just hours before she died."

More than 1 million people have viewed her message on TikTok since it was posted on June 1. And more than 3,000 users have commented, with many sending their condolences.

Her brother says she lived her life with transparency in "both the good and bad" and "let herself feel," which is a lasting message "for all of us to really embrace life."

For Rodenhausen, seeing the "beautiful" outpouring of support it's inspired for their daughters in particular has felt like a touching final gift from his wife.

He adds, "I just loved her incredibly over those 22 years, and we had a wonderful family."

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