Giving evidence at her former husband's retrial, Cindy Gambino said Robert Farquharson had arrived at her house about 7.40pm on Father's Day to tell her the children were dead.
''He was dripping wet and he said something like 'I've killed the kids' or 'They're in the water','' she told the Victorian Supreme Court yesterday.
''He was crying, he was hysterical in some ways, but he was babbling.''
Farquharson has pleaded not guilty to murdering sons Jai, 10, Tyler, 7, and Bailey, 2, on September 4, 2005, claiming he had a coughing fit and had blacked out when the car left the road.
Ms Gambino said she immediately grabbed her car keys and drove herself, Farquharson and her partner's son to the scene. She said Farquharson had been silent in the back seat as she reached speeds of 145 km/h before stopping on the Princes Highway. She had searched for a broken fence, tyre marks or the dam but said she had trouble seeing because it was so dark.
The court heard she ran up and down a paddock as she repeatedly yelled, ''Please, God, not my babies, please don't take my babies.''
Ms Gambino described her former husband's demeanour at the dam as unemotional. She said that apart from asking for a cigarette he had done nothing, as others - including her partner, Stephen Moules, who had gone to the scene - repeatedly dived into the water to try to find her children.
''He was like he'd lost his pushbike,'' she said. She said her sons had told her they wanted to stay with Farquharson for dinner when she dropped them off that afternoon.
After watching Farquharson open his Father's Day presents - a framed photo of the three boys, which she said he became emotional about, and a set of saucepans - she recalled asking him how 7.30pm sounded for him to return the boys to her. ''It's the biggest regret in my life, asking that question,'' she said.
She told Jai and Tyler she loved them, while Bailey's last words to her were ''Cuddle, mum''.
''I cuddled him and I left and that was the last time I saw them alive,'' she said.
The court heard Farquharson's relationship with his boys had been ''love-hate'', and he had frequently tormented his eldest sons. She said the boys had not respected their father, and said Farquharson's explanation for never smacking them was: ''Because if I was really angry, I wouldn't know when to stop. I wouldn't know how far I'd go.''
Ms Gambino admitted the boys' relationship with their father had improved following her separation from him in late 2004.
She said he resented her for keeping the newer car after the separation while he kept their 1989 VN Commodore sedan, which always needed repairs.
Recalling a phone conversation with Farquharson on the Wednesday before her children died, she said he had sounded ''really down and out''. He had felt he could not get ahead because of the $340 he had to pay in child maintenance each month, which was about to increase, she said.
''It ended up not getting increased because the children died so he didn't have to pay maintenance any more.''
The trial before Justice Lex Lasry continues.