A judge spoke of the "full horror" of addiction as he jailed a man for killing his partner during a row while they were both on drugs.
Michelle Harkett was found in the flat she shared with Donne
Jonathan Donne, 31, butted and then stabbed Michelle Harkett, 36, at a flat they shared in central Swansea.
He admitted manslaughter after it was accepted he did not intend to kill her.
Sentencing at Swansea Crown Court, Mr Justice Saunders said Donne should not be released until it was clear he had kicked his addiction to drugs.
The judge said that Donne, who had pleaded guilty at an earlier hearing, was "passive and harmless" when not on drugs.
But he became violent when high on heroin and cocaine and for that reason he defined him as a danger to the public under the Criminal Justice Act of 2003.
Malcolm Bishop, prosecuting, said Donne and Miss Harkett had shared a flat in Griffith John Street.
Late on 15 May last year they took a cocktail of Class A drugs and "a fearful argument" broke out.
Donne butted her in the face and she went into the kitchen, returning with several knives.
Ms Harkett's body was discovered at this block of flats
He threw her to the floor, took one of the knives from her and stabbed her twice to the neck and once through the heart.
The following morning the caretaker of the flats saw Donne on a stairwell.
He told him: "Something has happened to my missus. Phone for an ambulance."
Two police community support officers happened to be at the flats and they found Miss Harkett's body.
Donne was arrested, and at first he tried to blame someone else for Miss Harkett's death and then claimed he had acted in self-defence.
Mr Bishop said Donne's plea of not guilty to murder had been accepted by the prosecution on the grounds that he had not intended to kill her.
Sentencing Donne, Mr Justice Saunders said: "This is a tragic and difficult case.
"It demonstrates the full horror of what can happen to people who are addicted to Class A drugs. As a direct consequence Miss Harkett is dead and the defendant faces a jail sentence."
The judge added that no-one could be sure whether Donne would be able to overcome his addiction and he should not be released from jail until he could prove he had.