Corey Simms admitted to cheating on Miranda with Leah Messer during last week's Teen Mom 2, and now, fans are learning Messer was also cheating at the time.

'Teen Mom 2' Star Leah Messer Doesn't Want To Know What Fans Think Of Her Affair With Corey Simms

Although it is unclear when Simms' affair with Messer took place, he confirmed the hookup was during his relationship with Miranda, which means Messer was married to her second husband, Jeremy Calvert, at the time.

According to a Starcasm report in Nov. 2012, it was revealed that Messer began dating Calvert in 2011, and married him in April 2012. Meanwhile, a second report, also by Starcasm, claimed the start of Simms' relationship with MIranda took place in June of 2012, after Messer and Calvert had wed.

Corey Simms Claims His Kids Told Him Leah Messer's Boyfriend Sleeps In Her Home

In September, The Ashley's Reality Roundup confirmed Messer's affair with Simms, revealing it took place sometime in 2014, prior to Calvert filing for divorce in November of that year. Ironically, in Oct. 2014, Calvert took to Twitter, where he claimed to have caught Messer cheating, but noted her ex-boyfriend, Robbie Kidd, as the man behind her alleged affair (Kidd later gave a magazine interview regarding his alleged affair with Messer, claiming it did, in fact, happen).

While Messer's second marriage ended in divorce, Simms' marriage remains intact.

“Corey regrets it, especially since Miranda is pregnant now,” a source revealed. “But he had been talking to Leah for a while, so they both knew what they were doing. It wasn’t just a random mistake. But Miranda forgave him.”

Tags: Corey Simms Miranda Simms leah messer Jeremy Calvert MTV Reality TV Teen Mom 2