Hayley loses her cool on the stand in Thursday's Fair City on RTÉ One and the RTÉ Player.
Mondo is on trial over the death of Hayley's father, Anto, and Hayley is being cross-examined by Mondo's barrister, Clodagh O'Donnell.
Complicating matters, Anto had a relationship with Clodagh O'Donnell when they were both in rehab.
During her evidence in Thursday's episode, Hayley says angrily: "I begged him to leave my Da alone, but he wouldn't stop until he murdered him."
"I understand your anger, but you lied in your statement," says Clodagh O'Donnell.
"You're the liar, you drunken slut!" shouts Hayley.
Fans can find out what happens next on Thursday on RTÉ One and the RTÉ Player at 8:00pm.
Fair City airs on RTÉ One and the RTÉ Player on Sundays, Tuesdays, Thursdays, and Fridays.
