A Colorado man accused of killing his family also had a mistress, who recently came forward with shocking details about their relationship.

Chris Watts from the town of Frederick was arrested and charged with three counts of first-degree murder in the deaths of his wife Shanann, who was 15 weeks pregnant, and their daughters — four-year-old Bella and three-year-old Celeste — in addition to unlawful termination of a pregnancy and other felonies.

The murders took place Aug. 13. Shanann was killed after her return from a business trip in Arizona. The police believe the children were murdered before their mother came home, Mirror Online reported. 

A footage from a surveillance camera near their house showed Watts backing his car into the driveway early morning on that day and then showed him leaving in the vehicle after a while.

The bodies of the deceased were found on property owned by Anadarko Petroleum Corp, where the suspect was employed as an operator, the following day. Watts was arrested Aug. 15. Detectives are still working to establish a motive behind the killings.

Watts admitted to killing his wife, but denied having to do anything with the deaths of his children. He said he confessed to Shanann about cheating on her after she returned from her trip, and told her he wanted a separation. Hearing his confession, Shanann allegedly strangled their children to death. After witnessing his wife’s actions, he flew into rage and ended up strangling her.

Following his arrest, a woman who claimed to be Watts’ mistress, spoke to Radar Online, sharing details about their alleged affair between May and June this year. The affair began on Tinder and ended weeks before the murders took place.

"He would put his hands on my throat during intercourse. Now that I know who he is, it gives me the chills! I can’t even think about it. But nothing about him alarmed me until he tried to choke me. That freaked me out. He had a rape fantasy. He was very kinky. When we had sex, it was very animalistic. He just zoned out into a different person. He wasn’t the kind of guy who would cuddle and watch a movie,” the unnamed woman told the publication.

Watts reportedly used someone else’s picture on Tinder and told the woman he was already separated from his wife at the time. The mistress added she suspected him of having an affair with someone else as he was frequently “sneaking around.” After he stopped taking her out for dates, she said she felt like he was “using her for sex” and their relationship ended shortly after.

There has been indications to prove Watts was bisexual. An anonymous man called a live news show to confess he had met Watts in a gay dating app and dated him for a while.

According to prosecutors, Watts could be facing death penalty if convicted.