The Big Brother star branded Cipriani a "bulls**tter" earlier this week after the rugby player, whom she claimed to be dating, was pictured leaving a friend's house with Price.
Price has claimed that Thomas was behind a 2009 video which surfaced online showing her dancing and swearing in front of her children following her split from Peter Andre.
Thomas, who denied the accusations and hasn't spoke to the model since, thinks that this prompted Price to steal her boyfriend, according to The Sun.
A friend of Thomas's told the paper: "She thinks it's revenge. She loathes Katie over Danny and is raging she'll get her. She says Katie knew she'd started seeing him."
Price recently split from her boyfriend Leandro Penna. Meanwhile, Thomas is said to be preparing to star in The Bachelorette.