The mistress of accused killer Chris Watts has spoken publicly for the first time about the “horrific” murders that she says made her see Watts for who he really was—“a liar.” Watts, a Colorado father who pleaded guilty this month to killing his two young daughters and pregnant wife, had earlier admitted to investigators that he was having an affair with a co-worker, a fact that some saw as motive. In an interview with The Denver Post on Thursday, the co-worker, Nichol Kessinger, spoke publicly for the first time to say Watts had duped her into believing he was a doting father finalizing a divorce. In their two-month relationship, she said, she had no idea he had a baby on the way. Kessinger said she began to see red flags after Watts’ wife, Shanann, disappeared with the couple’s two daughters, Bella, 4, and Celeste, 3, in mid-August, and Kessinger realized he was still married and living with his family. “I thought, ‘If he was able to lie to me and hide something that big, what else was he lying about?’” she told the Post. Kessinger says she has never doubted that Watts killed his family, and his claim that he killed his wife in a rage after catching her strangling one of the children was nonsense, she said. “He’s a liar. He lied about everything,” she said. Watts now faces life in prison, with a sentencing hearing set for Nov. 19.