After 13 months of questioning police, lawyers, courts and the coroner's office, she heard for the first time yesterday from Judge James Weir that Tiumalu knew about the abusive texts.
Tiumalu had told her during a restorative justice session that he had no idea, and he was going to leave his wife and stand by the 15-year-old when she thought she was pregnant.
"It was so unbelievable. Most of what the judge told us we didn't know. It was so devastating that we had to leave," the mother said.
She felt betrayed and lied to, and had no problem with Tiumalu being sent to jail.
She wished Tiumalu or his wife had let her know he was leaving her daughter so she could have helped her.
"The judge was right. They had so many chances to let us know."
The 15-year-old died in hospital after her brother found her on the family's bathroom floor.