Susan Colquhoun, 42, stabbed Alan Kopp, 30, at his home in Hamilton, South Lanarkshire, in January last year. She then washed her hands, wiped the knife clean and threw it from the balcony of the flat.
After dialling 999, she claimed Mr Kopp had staggered home injured after being attacked in the street. The death led to a full-scale police investigation and more than 400 witnesses were questioned.
But, a court heard, Colquhoun told a friend what she had done.
She was later convicted of culpable homicide and attempting to defeat the ends of justice.
Sentencing her yesterday at the High Court in Edinburgh, Judge Lady Stacey told Colquhoun: "You lied to police. In doing so you made things worse for Mr Kopp's family."