Attar Khan, thought to be of South Asian origin, admitted attacking the woman, who he knew, on January six at her flat in Watford.
The victim, who has mental health issues, was stabbed and beaten over several hours, St Albans Crown Court was told. She went to police after he sent her to buy tobacco the next day.
He was jailed for 11 years last Friday, the BBC reported today.
His victim was stabbed and cut as she tried to defend herself against the attack which left her with a swollen and bruised face, and multiple "gaping" lacerations.
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During the prolonged assault Khan filmed her eating food he had contaminated with his own faeces, and brushing her teeth with a toothbrush similarly contaminated.
At one point he made her get on her knees and beg for forgiveness, the court heard.
The woman went to police when her attacker allowed her to leave her home to get tobacco for him.
The court was told unemployed Khan had 18 previous convictions and spent his time drinking and taking drugs.
Sentencing him to 11 years in jail and a further four years on licence, Judge Plumstead told Khan: "It was a ferocious, sadistic and violent attack.
"You were brutal towards this young woman. She suffered really serious harm at your hands. You battered her.