Ellie, three, and Isobelle, one, were named as Kerry Hughes' daughters
A man believed to have killed his two young daughters before killing himself had already told their mother he would commit suicide, a friend says.
David Cass and the girls' mother, named as Kerry Hughes, split up after a "stormy" relationship, Emma Timberlake has said.
Ms Timberlake said Ms Hughes, 20, told her Mr Cass would kill himself but said nothing about harming the girls.
Police found the bodies of Mr Cass, 33, and the girls in Southampton on Sunday.
The girls have been named locally as Ellie, three, and 12-month-old Isobelle.
Hampshire police believe Mr Cass killed his daughters before hanging himself at Paynes Road Car Sales, Freemantle.
Police are not looking for anyone else in connection with the deaths.
Twenty-year-old Ms Timberlake, who said she was a previous girlfriend of Mr Cass, explained he was "mentally unstable" and had lied about having large sums of money and a number of houses, rather than living in the caravan the bodies were found in.
"I spoke to Kerry on Friday and she told me that Dave had said he was going to kill himself," she said. "But he didn't say anything about harming the children.
"But when we were together and we broke up he has said the same thing to me, so I said to her 'Don't listen to him, darling', but then this happened.
Police were called to the garage on Sunday evening
"She still loved him and she wanted to make a go of it for the sake of the children but there had always been problems."
Family friend Val Frazier said she phoned 999 to alert police to what was happening.
Ms Frazier said: "[Ms Hughes] had a phone call [from Mr Cass] and he apparently said to her, 'The children have gone to sleep forever and now I'm going to hang myself'.
"She phoned straight here screaming and I just ran straight around and sorted it out with the police.
"It just won't go into my head that a man can take his own kids."
'Devoted to girls'
Formal identification of the bodies is expected later, following post-mortem examinations at the Royal Hampshire County Hospital in Winchester.
Forensic science officers have been examining both the caravan and the inside of the garage, which was cordoned off just before 1900 BST on Sunday.
Mr Cass's manager at the garage, John Martin, told BBC News that the MOT tester was devoted to his daughters.
He said: "That's all he talked about in here. He didn't want to live without his girls, I suppose, but I just took it as Dave being a little bit down."