Dean McDermott Says Sex with Tori Spelling 'Wasn't Fantastic'
04/21/2014 AT 05:10 PM EDT
In a scene from the upcoming docudrama, Dean McDermott confirms he wasn't happy with his and wife Tori Spelling's sex life – a problem that led him to infidelity and, in January, rehab.
"We would have sex once every two weeks," McDermott, 47, says during an April 9 therapy session. "It wasn't fantastic."
As Spelling, 40, protests, their counselor calls him out.
"Dean, your expectations of what a marriage is supposed to be sexually, it's like a fairy tale," she says.
Married in 2006 after meeting on a movie set and leaving their respective spouses, Spelling and McDermott have four children together: Liam, 7, Stella, 5, Hattie, 2, and Finn, 20 months.
The actors have never shied away from cameras, sharing their love story on reality shows Tori & Dean: Inn Love and Tori & Dean: Home Sweet Hollywood. But Lifetime's True Tori, premiering Tuesday, tells a very different tale of heartbreak and betrayal.
"I'm insatiable," McDermott admits in the sneak peek. "Sex was an escape, just like drugs and alcohol."
"But I don't understand, like why her?" Spelling tearfully asks of his mistress.
"I wasn't attracted to her," he says. "It was just like a warm body."
The final blow comes after a confession from McDermott already heard in a previous clip: "I cheated on my wife. That's my worst nightmare."
But Spelling isn't convinced, adding, "Or that you got caught."
McDermott's response? "I don't know."
True Tori airs Tuesday (10 p.m. ET) on Lifetime.