A woman who killed her toddler daughter and baby son has told a court she was "a good mum, and I never meant any of this to happen."
Felicia Boots, 35, who suffered from post-natal depression, pleaded not to be judged harshly for killing Mason, nine weeks, and Lily, 14 months at the home she shared with her husband Jeff in Wandsworth, south London, in May.
Boots wept at the Old Bailey as she admitted the killings. She pleaded guilty to manslaughter on the grounds of diminished responsibility.
She was ordered to be detained at a psychiatric unit and the court was told she would be given full support and care if she became pregnant again.
Boots, who wore a black suit and white blouse, sent a note to the court which was read by her counsel Kate Bex.
It said: "May 9, 2012, is a day I will be eternally sorry for. It should never have happened.
"It troubles me more than anyone will ever know. Part of me will always be missing. I am a good person. I am a good mum and I never meant any of this to happen. I am truly sorry."
Details of the babies' injuries were not detailed, other than to say they had been asphyxiated.
The court was told that Boots suffered postnatal depression following the births of both children, but appeared to be getting better.
She was prescribed antidepressants but had not been taking them after becoming convinced the babies would be taken away from her because of the effects of the drugs on her breast milk.
Edward Brown QC, prosecuting, said Mr Boots was supporting his wife.
He said: "This plainly is a tragic case. There were signs Mrs Boots had made an attempt on her own life. She had marks to her neck."
The couple married in 2007 and came to the UK from Canada. "They were a happy family and they were comfortably well-off," he said.
They had recently moved house and some of their possessions were still in packing cases.
Mr Boots went to work on May 9 as normal. He received a photo-text of Lily from his wife.
But when he arrived home the house was in darkness and he found his wife on the stairs, hugging herself and curled up.
Mr Brown said: "Mr Boots ran past her and found their two children lying lifeless on the floor of a walk-in cupboard off the main bedroom.
"He very soon returned, very distressed, to his wife. On questioning, she told him she had killed the children at 2pm. She also said she had tried to kill herself."
The judge, Mr Justice Fulford, said: "A prison sentence would be wholly inappropriate in this case."
He added: "This is an almost indescribably sad case.
"Although the results of Mrs Boots' actions were profoundly tragic given the loss of two young lives, what occurred was not criminal activity in the sense that expression is normally understood.
"I unreservedly accept that what she did to the two children, that she and her husband loved and nurtured, were the results of physical and biological factors beyond her control."
There was no doubt of the strength of the relationship between the couple. "This has always been a happy family," he said.
"This is someone who delighted in being a mother and she was good at it."
He said Boots may have hidden the extent of her mental anguish from her husband and family.
The judge did not impose any restriction on the time Boots would be detained.
Mr Boots and his family said they did not wish to make any further comments about the case.