Martina Harding will be eligible for parole in about 19 years.
The 45-year-old pleaded guilty to aggravated manslaughter in the 2007 attack in her family's home in Deptford. Under a plea deal, Harding withdrew the defense of not guilty by reason of insanity.
Harding's son, Jarod, was slashed in the throat. The attack was witnessed by his 9-year-old sister.
Harding said during her plea hearing that she was depressed and was suicidal on the day of the attack.
At sentencing Thursday, Harding told the court she lives with the memory of her actions every day.
