Martha Stewart Admits to Cheating on Ex-Husband During 29-Year Marriage

Martha Stewart may seem picture-perfect in the media, but the lifestyle guru is admitting to a flaw in her past ... she's confessed to cheating on her ex-husband, Andrew Stewart .

The business mogul shares the shocking revelation in a trailer for her upcoming Netflix documentary, in which she advises women to leave their husbands if they're discovered to be unfaithful.

As she puts it ... men who cheat are "piece[s] of s***" ... though, she's a lot more forgiving of women who stray, given her own past.

When confronted with her prior infidelity -- an affair "early on" in her marriage -- she quips ... "Yeah, but I don’t think Andy ever knew about that."

Martha and Andrew were married back in 1961, welcoming daughter, Alexis , years later in 1965. However, the pair called it quits in 1990 after nearly 30 years of marriage.

The TV personality is expected to share more about her personal life -- including her 2004 stint in federal prison -- when her new doc, aptly titled, "Martha," drops on October 30.

MARTHA STEWART THROUGH THE YEARS

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Though Martha went on to date in the public eye after her divorce, having been linked to actor Anthony Hopkins and software architect Charles Simonyi in the past, she appears to be currently single ... and seems perfectly content in keeping it that way.