Water polo coach Lilie James was killed when her ex-boyfriend Paul Thijssen bludgeoned her over the head with a hammer at least 25 times in a bathroom at St Andrew's Cathedral School in Sydney on October 25, 2023.
Speaking at an inquest into her death on Thursday, Ms James' devastated parents Peta and Jamie stressed the need for cultural change to prevent more women being killed.
"As parents, if we are not teaching our sons how to respect a woman's opinions and choices and accept rejection, we could be setting our daughters up for failure," Mrs James said through tears.
"In our case, a moment in time we will never recover from."
They mourned the loss of their beautiful, independent and adventurous daughter who had a wicked sense of humour and a smile that could light up a room.
"Lilie, sweetpea, I am so sorry we couldn't protect you from what happened that night," Mrs James said.
"The guilt that I feel will stay with us forever."
Coroner Teresa O'Sullivan thanked the James family for their powerful presence throughout the inquest and said she was sure their participation would save lives.
Their tribute came after the release of chilling footage showing Thijssen outside the bathroom moments before killing the 21-year-old.
Ms James ended their casual two-month relationship five days before she was killed in the bathroom and Thijssen took his own life.
Domestic violence expert Anna Butler said patterns of coercive control were evident throughout their short relationship.
When Ms James had previously tried to break up with Thijssen, he used degrading, derogatory, and gaslighting language to erode her autonomy.
He escalated his emotionally abusive behaviour when he shared an intimate image of the 21-year-old with friends and stalked her when she said she wanted to split up.
Ms Butler said Thijssen felt growing anger and resentment that he no longer controlled their status, so he used a cache of well-honed manipulative tactics to try to regain control.
In her closing remarks, counsel assisting the coroner Jennifer Single SC agreed there was no prior indication he was going to take Ms James' life and end his own.
Ms O'Sullivan will hand down her findings at a later date. With AAP.
