A Texas middle school teacher has been charged with sexual assault for allegedly having an affair with a teenage student, who later went on to extort tens of thousands of dollars from her in exchange for his silence, according to police.

Thao ‘Sandy’ Doan, a 27-year-old social studies teacher at Raul Quintanilla Middle School in Dallas, was arrested on Friday in connection to the suspected sexual relationship.

According to an arrest affidavit cited by Dallas News, the mother of a 14-year-old boy went to the authorities earlier this month complaining that her son was getting large sums of money from Doan and using the cash to buy alcohol and drugs.

The parent also shared with investigators screenshots of text messages suggesting that her son, a former student at Quintanilla Middle School, had been blackmailing his teacher-turned-lover.

One message allegedly read: ‘Aint b’sing watch ima start getting the pics and everything ready to show the cops. Right i aint playing.’

Police believe the teen forced Sandy Doan to pay him about $28,000 in several cash installments after threatening to tell the authorities about their sex romps.

When interviewed by police, the 27-year-old woman reportedly admitted that she and the 14-year-old had communicated via text messages, on Instagram and on the app Kik before meeting for the first time to have sex at a park in the summer of 2015.

At one point, the teacher allegedly sent the boy a photo of her naked breasts, reported WFAA via WLS.

The arrest document states that Doan and the boy had several more trysts between November and December 2015.

The boy’s uncle told the station WFAA his young nephew seemed ‘smitten’ with his teacher, whom he later came to regard as his personal ‘piggy bank.’

In January 2016, Doan said she began receiving extortion calls from someone she did not know threatening to expose her illicit affair with the student if she refused to pay up.

Despite the unfolding blackmail scheme, Doan said she had sex with the teen again in December 2016.

According to Quintanilla Middle School’s website, Doan teaches sixth grade and works as a soccer and cross country coach.

She has been placed on administrative leave in the wake of her arrest.

The student at the center of the alleged extortion plot is not expected to face criminal charges in the case.