A California man is accused of fatally shooting his ex-girlfriend’s new fiancé, a beloved high school teacher, after complaining that he felt “betrayed” by their breakup.

Jesse Alvarez, 30, was arrested Monday night in the murder of Cathedral Catholic High School teacher Mario Fierro in North Park, news station CBS8 reported.

He allegedly shot the 37-year-old educator earlier that morning as he was leaving his home, police said.

Fierro, who taught social science, was pronounced dead at the scene, authorities said.

Fierro had recently become engaged to another colleague, who had dated Alvarez for more than three years before she broke things off in 2019, according to court records.

The woman had sought a restraining order in December 2019 against Alvarez, claiming that she was “scared and fear for my safety.”

She alleged that she had spotted Alvarez “looking through the windows” at her home and that he showed up to Disneyland after following her into the park, according to court documents.

Despite her blocking his number, he would use different phones to contact her, calling anywhere from 20 to 30 times, she said.

She also claimed that Alvarez tried to use an old key to break into her apartment after she had installed home security cameras and changed the locks, news station KNSD reported.

Alvarez denied that his ex-girlfriend was in danger, claiming there was “no credible basis of threat towards her.”

“She is intentionally acting out of spite, hate and malice in order to personally hurt me, damage my reputation, restrict my civil liberties and sabotage my career by blotting my stainless legal record with the court,” he wrote in court documents, KNSD reported.

He admitted that he “felt hurt and betrayed” by their relationship ending, but “never ever abused or mistreated” his former girlfriend, according to court documents.

The judge ultimately dismissed the request for a restraining order, ruling that the woman “did not meet her burden of proof,” news station 10News reported.

Alvarez was booked into San Diego Central Jail, where he’s being held without bail, the outlets reported. He’s set to be arraigned Feb. 19.