Katey Renieta Gonzales stabbed 17-year-old Angela Qiu five times at a booze-fuelled party in May 2010.
She was charged with one count of second-degree murder, but pleaded guilty to manslaughter last month.
Fighting back tears in Vancouver Supreme Court on Wednesday, the 22-year-old apologized to the Qiu family and said it was difficult to live with what she had done.
While severely intoxicated, Gonzalez had stepped into a disagreement between Qiu and a young man at the house party, and was handed a knife by another party-goer. Qiu ended up with fatal wounds.
Gonzales fled the scene, but turned herself in the next day.
Qiu's family did not appear in court, but her mother said in a victim impact statement that she had been gravely traumatized by her daughter’s death.
"The brutality of this crime has not only killed my daughter, but ruined my family," the statement said.
Crown lawyers have asked for a sentence of eight years in prison, while the defence is seeking a five-year term.
The sentence will be delivered on July 2.