The ex-girlfriend of Patrick Frazee, the man accused of killing missing Colorado mother Kelsey Berreth, will appear on Dateline Friday night to reveal details about a relationship she characterized as abusive.

NBC News reports that Vanessa Curie and her mother will appear on Friday’s episode of “Dateline,” and shared a preview clip of the interview.

“He had no empathy for life,” Currie reportedly told “Dateline” about Frazee. “He’s a monster.”

Currie told the news program that she started dating Frazee in 2010 and enjoyed his company in the beginning; but that he began to show a dark side about four months in.

I was attracted to his sharp wit and he had a very explorative mind. He contemplated everything. And he was excellent at reading people,” Currie said.

But things changed.

“He began not calling me for days, and then calling me in the middle of the night telling me he had visions of me in a wedding dress. And we’d talk and argue for hours. And we’d end up winding right back into each other.”

Eventually, Currie said, she ended the relationship after she found the definition of a psychopath online.

“He fit the bill to a T. And that’s when I left him.”

Frazee was arrested in December for the presumed murder of his fiancee Kelsey Berreth, 29, who has not been seen since Thanksgiving Day. Investigators are currently searching a Colorado landfill for evidence of Berreth’s body. Authorities said following Frazee’s arrest that they believe Berreth was killed in her Woodland Park, Colorado, home.  Frazee’s friend Krystal Lee Kenney, who entered into a plea deal in exchange for her cooperation as a witness, reportedly said Frazee told her he hit Berreth over the head with a bat.

Tune into “Dateline” on Friday 10pm ET/9CT.