Marnie Simpson sat and watched the video showing Lewis Bloor cheating on her.
The 25-year-old reality TV star - who separated from Lewis earlier this year - has recalled the bizarre circumstances surrounding her split from Lewis, after a video leaked showing her ex-boyfriend romping in bed with another woman.
Speaking to Gemma Collins and Nicola McLean on "Celebrity Big Brother", Marnie explained: "I watched the video of him cheating on us.
"Cause I got tagged in this video and he was in the bed with her and she was on top of him but the quilt was over them and they were, like, kissing.
"It looked like they were having sex but I wasn't sure so I messenged her."
Nicola then interrupted Marnie and asked who would have made the X-rated video.
Marnie replied: "Her friend. She must've been standing at the other side of the room.
"There was music on. He obviously didn't know that they were getting filmed."
Marnie admitted her heartache was compounded by the fact Lewis cheated on her on Valentine's Day.
She said: "He took two of them back to the hotel - on Valentine night of all nights."
Marnie subsequently confronted one of the women who appeared in the sex tape, describing her as "scum".
She shared: "She went "Just so you're aware, I was fully clothed under the covers we didn't have sex and I'm really sorry".
"I was like "why did you release it? why didn't you just send it to me?" She just gave us a stupid excuse and said "sorry". I said "Girls like you aren't sorry. You're scum.""