The 30-year-old actress explained that she found herself in the steamy situation after meeting a man in a pub and exchanging some flirty texts.
Reflecting on the past fling on her new ITV2 series The Emily Attack Show, the former I'm A Celebrity star joked that it wasn't easy breaking up with the man and woman at the same time after they both fell in love with her.
The Sun reports that Emily didn't know that the man she met in the pub was married at first.
She told the publication: "After a bit of flirting and texting, he announces that he's married but it's OK because he and his wife have an open relationship and she wants to meet me.
"'Now to some people that would be a red flag but I'm like a bull — red flags drive me wild.
"It was all fun... for a bit until they both started falling in love with me."
Emily decided to call it quits and told the couple that they needed to sort out their problems, telling them "s****ing me is not the answer".
Speaking on her show, she joked that 'breaking up with two people' at the same time was very 'awkward'.
Emily has never shied away from sharing details about her personal life and even teased a huge revelation was coming up in her show back at the start of November.
The beauty recently admitted that she was sick of her brother George threatening to tell everyone her shocking secret so she decided to beat him to it.
The Inbetweeners actress told The Mirror: "He's had this reign of terror on me for years, so I thought 'Right, I'm getting this out in the open''."
Emily admitted that her parents Kate Robbins and Keith Atack were gobsmacked after she revealed the secret "no parent should have to hear" on her show.
The new Celebrity Juice captain also teased that the revelation will be broadcast on an upcoming episode and her mother Kate was left "covering my dad's ears".
Despite the teaser, Emily did not reveal what the shocking secret was and it is not known if she was referring to the tale of her past threesomes.
The Emily Atack Show airs on ITV2 on Wednesday nights at 10pm