TYLER, Texas (AP) — A 39-year-old woman who had sexual relationship with her teenage stepson and later gave birth to their child has been sentenced to 20 years in prison.

Carla Kay Dinger pleaded guilty to sexual assault of a child before Tuesday's sentencing. She was also ordered to pay a $10,000 fine.

She admitted carrying on a sexual relationship for two years with her then-stepson, starting in 1998 when he was 14. It ended when Dinger found out she was pregnant with her stepson's child, prosecutor Jason Parrish said.

The stepson told his mother about the relationship in 2001, and she told Dinger's husband. He confronted Dinger and she admitted to the affair, Dinger has said. Dinger and the teen's father divorced in 2002.

The child she had with the teen is now 6 years old. Dinger had primary custody until 2004, when she and her ex-husband began sharing custody.

Dinger has tried to change her life, going to counseling and attending church, said her attorney, Clifton Holmes. She owns and operates a medical equipment business in Tyler, about 100 miles southeast of Dallas.

Dinger's former stepson, now 22, filed a lawsuit in 2004 against her seeking monetary damages.

In the lawsuit, he said Dinger had frequently provided him with methampetamines and alcohol.

The two had made plans for Dinger to divorce his father so they could marry, he said. But after Dinger found out she was pregnant, she sent him to live with his mother and told him not to tell anyone, he said.