Tad Cummins slept with teen student, his wife says

— -- The wife of the former Tennessee teacher who was discovered last week in a rural cabin after over a month on the run with his 15-year-old student, said that he told her that he slept with the teen.

Jill Cummins spoke out about 50-year-old Tad Cummins' alleged relationship with Elizabeth Thomas in an exclusive interview with "Inside Edition," saying that that she asked him, "'Did you sleep with her?' And he said, 'Yes, I did,' and so I did not want any details.

"I knew the truth, I just wanted to hear it from him," she added.

"He kept saying, 'I love you,' but I said 'I'm sorry, but I am not going to say that back,'" Jill Cummins said, adding that he begged her for forgiveness after he was taken into custody by authorities on April 20, 2017.

Tad Cummins led investigators on cross-country journey that lasted over a month before he was arrested in Northern California, according to the Tennessee Bureau of Investigation.

"It was very hard to hear his voice after all this time, not knowing if I was going to hear it again, but he told me he was sorry," Jill Cummins told "Inside Edition." "He told me that he loved me and ... please forgive him."

"I told him I wouldn't be answering the phone anymore," she added.

Jill Cummins told ABC News in a previous interview that she had filed for divorce from Tad Cummins, after more than 30 years of marriage.

Tad Cummins faces charges in Siskiyou County, California, for kidnapping and possession of stolen property, according to the sheriff's office. The charges are pending review by Siskiyou County District Attorney Kirk Andrus. In Lawrence County, Tennessee, Cummins faces charges of aggravated kidnapping and sexual contact with a minor, said Attorney General Brent Cooper.

The U.S. State Attorney's Office for the Middle District of Tennessee also filed a federal charge of transportation of a minor across state lines with intent of having criminal sexual intercourse against Cummins, said U.S. attorney Jack Smith. The charge carries a mandatory minimum sentence of 10 years in prison.

The 15-year-old victim's father, Anthony Thomas, told ABC News that his daughter's appearance changed during the time she was missing.

"She had lost some weight for sure," Anthony Thomas said. "He had not been feeding her. ... She said they had been eating flowers and things."

Elizabeth is currently spending time with her family and a trauma team to help her cope and heal.

ABC News' Alex Stone, Morgan Winsor, Eva Pilgrim and Julia Jacobo contributed to this report