The Tennessee teen who sparked a cross-country search when she disappeared with her teacher for weeks revealed for the first time his first creepy advances — and how he threatened to kill himself and hurt her family if she tried to escape.

Elizabeth Thomas was 15 when her health science teacher, Tad Cummins, sat across from her during fourth period and told her, “You’d look pretty nice naked,” according to an interview with ABC’s “20/20” that’ll air Friday.

Then 50-year-old Cummins kissed her, she said.

“I was scared,” recalled Thomas, now 17. “I didn’t want to tell my parents that a grown man kissed me. I didn’t want to tell my friends … Whenever he first kissed me, that’s when I realized it was getting too far.”

But, she continued, “I didn’t want to make him mad or make him come after me or anything like that.”

Before she was assigned to his class, Thomas had been home-schooled her entire life and was abused by her mother, according to reports.

“He made me feel like I didn’t have anyone else, and no one really cared about me like he did,” she said of her teacher.

To make her dependent on him, Cummins convinced the teen not to get the mental help she needed, Thomas said.

“I was feeling real low,” she said. “I was trying to get on antidepressants and go to a therapist and he told me no and not to do it, because it would change who I was.”

Then, on March 13, 2017, Thomas left home with luggage and reluctantly took off with her teacher.

Once in his car, she says, he pulled out a gun.

“As soon as we went to leave, he set a gun in the middle console and I knew that I wasn’t getting out of the car … that I wasn’t getting out of this,” she said. “He said if he couldn’t have me, he would kill himself,” she added. “Anytime he threatened himself, he threatened my family.”

The nationwide manhunt for the pair lasted more than a month. They eventually were found in a small shack in Northern California after a tip to authorities.

Even after he was caught, Cummins still tried to control the teen, she said.

“He said not to tell them that we had done anything [or] that he forced me to go,” she said. “To say that I went willingly, to say that he was trying to protect me.”

Thomas said there are a lot of misconceptions about what happened to her.

“They think they know what happened,” she said. “They think I like old men and that’s not the case. He made me feel like I didn’t have anyone, that nobody else cared about me like he did.”

The teen said she has finally learned to stop blaming herself for the ordeal.

“I know he’s a bad man and I blamed myself a lot, but now I know that he’s at fault, he himself made him do it,” she said. “Other people don’t choose your actions, you do.”

This spring, Cummins pleaded guilty to transporting a minor across state lines for the purpose of having criminal sexual intercourse and obstruction of justice. His sentencing hearing is scheduled for December.