It's not like Olivia didn't know her mother was after Aurora and not her father. She clearly knew this fact but couldn't help being furious about something else.
Why did her mother choose the night of her wedding of all days to attempt the assassination?
Somewhere in her mind, Olivia was thinking that her mother's atrocities might have been what jinxed her marriage and turned it beyond repair.
"You know it was a mistake. Do you think I'm that crazy to kill your father?" Stella asked, looking distorted. "Aurora was my target." Suddenly, she lowered her voice and continued discreetly, "How was I to know the waiter would leave her and kill off your father?"