The mentally unstable 39-year-old mother, a bakery saleswoman identified only as Bianca T., first strangled her six-year-old daughter, then smothered the four-month-old twins.
The woman acted in the throes of desperation after the twins' father committed himself to a psychiatric ward for depression and she could not convince him to return home.
In a harrowing testimony, the court heard how the terrified six-year-old, Anna-Lea, had struggled and pleaded for her life, saying "Mama, I don't want to die, not today, maybe tomorrow".
After the attacks on November 13th last year, the woman intended to take her own life and headed, with the children's bodies in her car, straight for a carpark to jump off the roof, having sent her partner text messages about the killings.
But the man called police who then spotted the woman in her car, leading to a high-speed chase. The woman deliberately crashed in a suicide attempt but walked away almost unscathed from the wreck, the court in Landshut, southern Germany, was told.
After her arrest, the mother confessed, claiming to have smothered the twins – a boy and a girl named Fabian and Lisa – but an autopsy later found both had also suffered fractured skulls and the boy broken limbs.
Anna-Lea and Fabian were declared dead in hospital, where surgeons attempted to save the life of Lisa before she too died of her injuries.
"I'm sorry, I'm so sorry," the woman said in tears in court, testifying that she had acted without a clear motive.
"I committed these acts, I know… But it's as if it wasn't me. It's like I was outside of myself," said the woman, who has had a total of six children from three fathers.
Prosecutors had demanded a sentence of 14 years and six months on murder and manslaughter charges for the woman, and the defence 13 years.
No appeal was scheduled.