EXCLUSIVE: Martha Stewart's Prison 'Bestie' Tells All — 'She Betrayed Me After I Saved Her Life'

It's been 20 years since Martha Stewart swapped her sprawling estate for a cramped prison cell after her infamous stock trading scandal.

But now, her "prison bestie" Lisa Guarino is spilling secrets about the domestic diva's five months behind bars – and claiming Stewart broke a heartfelt promise, RadarOnline.com can reveal.

"She told my family they no longer needed to put money on my books because she was going to take care of me", said Guarino, 62, a former inmate at Alderson Federal Prison Camp in West Virginia. "But Martha didn't keep her word. She gave me a doughnut – a big fat zero".

Guarino, once dubbed "Boston's cocaine queenpin", said she met the good living guru in the most unexpected way.

"I pulled back a curtain and saw this naked white butt right in front of me", she recalled with a laugh.

Despite the awkward introduction, the two bonded quickly over late-night laughs, shared meals, and the challenges of prison life at the facility, ironically nicknamed "Camp Cupcake".

When Stewart arrived at the prison on October 8, 2004, for a five-month stay, her new home was a far cry from the luxurious living she enjoyed on her 153-acre Katonah, N.Y., farm. Instead of a three-story mansion, Martha was placed in a tiny two-person room with bunk beds.

"It was horrifying," Stewart, 83, recalled. "It's a very, very awful thing."

And she faced immediate hostility.

Ex-inmate Evie Litwok explained: "In Alderson, everyone was required to work in the kitchen for their first 90 days. That is, everyone but Martha Stewart, who requested but was denied kitchen duty. I suspect she was refused because this chore might have given her an inkling of pleasure within the miserable prison environment.

"She was assigned instead to the humiliating task of mopping the floors and cleaning the toilets of the warden and other higher-ups."

Guarino said she became Stewart's guide to surviving prison life, teaching her how to transform commissary staples into edible dishes like "dirty pasta" and makeshift pies.

"Martha was amazed at what you could do with a microwave", Guarino said.

But prison wasn't all camaraderie and culinary experiments. Stewart's wealth and fame made her a target.

One night, a tough inmate named "Swish" threatened her life, Guarino claimed. "Martha was terrified. If it weren't for me stepping in, she could have been seriously hurt or worse."

According to Guarino, the media mogul leaned on her heavily behind bars, even calling her "the best friend I've ever had".

Stewart reportedly organized a going-away party for Guarino when she transferred to a drug treatment program, cementing what Guarino thought was an unbreakable bond.

But once the TV personality walked free, the relationship crumbled.

"I went to see her at an event promoting her 100th cookbook," Guarino said bitterly. "She ignored me completely and left through a side exit. I was offended."

Guarino, who cooked for Stewart, protected her and even saved her life feels abandoned and betrayed.

"I believed we were friends," she lamented. "But once she got back to her world, she went right back to her narcissistic ways."

While Stewart has spoken about her prison stint being "horrifying" and "awful", she's never addressed Guarino's claims – or her alleged promise to help her.

For now, the ex-inmate who once had Stewart's back is left wondering if their connection was real — or just a survival tactic in the harsh world behind bars.

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