A woman who met Colorado killer Chris Watts on Tinder is opening up about her short-lived affair with him.
"He seemed like a genuine guy," McMahon told Inside Edition. "He was funny. He was charming." She added that Watts told her he was divorced.
They texted at first, before eventually arranging to meet for tacos.
The relationship, McMahon said, lasted for several weeks.
Watts enjoyed "rough" sex, according to McMahon. "The best way I can describe it that he almost zoned out into a different person," she recalled.
At one point, he placed his hand around her neck, McMahon said, and she "freaked" out.
"Very forceful," she said.
The relationship ended when Watts began seeing another woman who was not his wife: co-worker Nichol Kessinger. Kessinger said Watts told her he was separated and finalizing his divorce.
The next time McMahon heard any news about Watts, he was making headlines for strangling his wife and smothering his two young daughters, 4-year-old Bella and 3-year-old Celeste, in mid-August.
Her immediate thought? "It made me feel betrayed," McMahon said. "It made me feel nasty. It made me feel dirty."
She said she would never have taken up with Watts had she known he had a wife.
"He was married, he had a wife at home, pregnant, two daughters at home," said McMahon. "I know how that hurts. I wouldn't do that to her."
There's also speculation that Watts was inspired to blame the death of his daughters on his wife by the 2010 movie "Shutter Island," starring Leonardo DiCaprio. In it, DiCaprio plays a husband who murders his wife in a rage after she kills their children.
After his initial arrest, Watts told investigators Shan'ann killed the children after he asked for a separation and he in turn strangled her in a rage.
He later confessed to all three murders to avoid the death penalty and was sentenced to five life sentences in late November.