Cynthia was also hit with the harmful substance charge after she put Dennis’ sperm into cupcakes that she gave to students at Livingston’s Westside Junior High School, authorities said.
Under the plea deal, Cynthia had 68 other charges against her dismissed and will have to testify against Dennis at his upcoming trial.
“She not only waived any right to appeal, and attempt to avoid conviction, but she also spared the victims from reliving her horrific crimes during this particular trial,” Louisiana Attorney General Jeff Landry said in a statement.
Cynthia will be sentenced to 41 years in prison on Friday, authorities said.
She filed for divorce from her husband in the wake of their arrests and alleged that Dennis had manipulated her into committing the crimes.
The couple were busted after authorities received a tip at the National Center for Missing and Exploited Children.
Investigators later found nude photos of them with the minor.
Cynthia resigned from Westside Junior High School the day after her arrest, while Dennis was fired from his deputy role at the Livingston Parish Sheriff’s Office.
Dennis is scheduled to face trial in May on 150 criminal charges.