Shaniece Dobson sagged in the dock at the High Court in Edinburgh as she was sentenced for the "deliberate and wicked" fatal attack on 21-year-old Sean Martin.
Dobson, 21, was originally charged with murdering Mr Martin at her flat in Coatbridge, in North Lanarkshire, a year ago. But a jury earlier found her guilty of the lesser charge of culpable homicide by striking the victim on the body with a knife. Mr Martin collapsed and died within minutes.
The judge also ordered Dobson should be kept under supervision for a further year after the custodial sentence.