Jill Cummins says the girl was like a daughter to her.
Tad Cummins' wife says she warned her husband against getting too close to his 15-year-old student after noticing they had been becoming friendly.
Speaking exclusively to Inside Edition, Jill Cummins said she and her husband had been trying to help Elizabeth Thomas through some tough times at home and thought of her as another daughter.
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But she noticed her husband and the teen were getting a little too friendly before vanishing together in March.
"He was getting really close to her," she said. "A father-daughter close, a friendship close, and I knew that. I discussed that with him. And explained to him, 'She's your student, you can't be so close to her.'"
But she added: "Never did I think there was a romantic thing between the two of them. There were no signs of that."
Jill, who filed for divorce from Tad when he disappeared with the teenager, agrees that Thomas was exploited and perhaps even brainwashed.
"I feel slightly betrayed by her because she knew me," she added. "I don't really want to talk to her. It's not the right time. Maybe one day."
A rep for Elizabeth Thomas called Tad Cummins a "classic predator" who brainwashed the teen into running away with him.
Jill also revealed that she played a key role behind the scenes when her husband took off. She made a moving television appeal for Cummins to turn himself in, which she said was her idea.
Jill also gave investigators every clue she could.
Read: Tad Cummins' Wife: He Told Me He Slept With Teenage Student
"They would send me pictures from surveillance cameras to get my opinion whether or not it was him," she claimed.
After five weeks, Cummins and the teenager were found at a remote cabin in Cecilville, Calif., when a tipster recognized them and called authorities.
Thomas was reunited with her family while Cummins was arrested. He appeared in court in Sacramento on Monday and faces one federal count of transporting a minor with the intent to engage in sexual activity across state lines.
He has not entered a plea. He's expected to be transported to federal court in Tennessee within weeks.
He faces a minimum sentence of 10 years and up to life in prison, if convicted.
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