A pregnant mother cut the throats of her son and daughter and took rat poison after being unable to cope as her husband ran a convenience store, the Old Bailey heard today.
Sasikala Navaneethan later alleged she did not want to live because her husband was beating her.
She said she stabbed and cut the throats of son Shanjayan, five, and daughter Sharani, four, and her six-month-old baby girl, because she did not want to leave them behind.
Police found the three children lined up on a bed at the family home in Park Lane, Carshalton, Surrey, in May last year.
Navaneethan, 37, pleaded guilty to two offences of manslaughter on the grounds of diminished responsibility.
She also pleaded guilty to the attempted murder of baby Trishana.
Navaneethan was sent to a mental hospital without limit of time.
Her husband Navarajah, 39, worked from 6.30am to 11pm running the shop and off licence in Brighton Road, Croydon.
Mr Navaneethan told police their family life was happy and the local medical centre said his wife had never complained of mental problems.
But the court heard Mrs Navaneethan had suffered a breakdown when she was around 18 during the Sri Lankan civil war before coming to Britain.
She told psychiatrists she had been suffering from depression after Trishana's birth and having delusions.
Dr Paul Chesterman said she had reacted to her domestic situation, sense of isolation and because of her mental illness.
The Common Serjeant, Judge Brian Barker, told Navaneethan: "This is a profoundly sad and tragic case.
"It seems to me your turmoil and your actions are virtually impossible for an outsider to understand.
"This is the case of a sick person who continues to be sick now. You need treatment rather than punishment."
David Etherington QC, defending, said cultural expectations may have resulted in Navaneethan being unable to tell her GP she was mentally unwell.
"She believed there was no point in her living any longer and she could not leave the children with her husband," he said.
Navaneethan had responded to medication and was filled with terrible guilty about what she had done.