Maria Ann Jones, 42, and the man were at her Moat Road home listening to music and drinking late into the night on February 6 last year, when they argued about the tune and she attacked him with large kitchen knife, leaving him with serious injuries.
Rachel Pennington, prosecuting, told Wolverhampton Crown Court that the pair had been in a six-year relationship, but lived at separate addresses.
"They listened to music, but at about 1am the victim noticed that the atmosphere changed and he went out to buy alcohol. There appears to have been an ongoing argument over who knew the words to a particular song.
"The victim recalls some sort of threat was made and he decided to keep an eye on on what the defendant was doing. She went into the kitchen. He saw her take a knife from the kitchen drawer. He got up to close the door and told her to 'stop'.
"He then opened the door and the defendant stabbed him with the knife. He was shouting and asked her to call the ambulance. She didn't immediately act.
"CCTV inside the property shows that at some stage the victim laying or climbing over the defendant."
Miss Pennington said Jones, who has a mental disorder, was captured on CCTV entering the lounge with the weapon.
She said that after stabbing the man Jones failed to assist him and delayed phoning for an ambulance. Paramedics eventually arrived after 5.40am to find him slumped between two sofas.
He had suffered a gaping two-inch wound and was taken to the Queen Elizabeth Hospital, in Birmingham, for emergency trauma surgery. The court heard he need further surgery and suffered a brain bleed as a result of his injuries.
Miss Pennington read aloud part of the man's police statement in which he described feeling "betrayed" by Jones, who admitted an offence of wounding at an earlier hearing.
"I genuinely thought I was going to die," he stated.
Sentencing the support worker, Recorder Abigail Nixon said it had be a "failing" of the Crown Prosecution Service case that no written record was taken of whether the victim suffered "life-threatening" injuries. And she said the defendant had been "lucky" not to have been charged with attempted murder.
"It is tragic to see somebody like you standing in crown court for this sort of offence which you have pleaded guilty to," she said.
"The report concludes that you do suffer from a mental disorder which was exacerbated by your use of alcohol which played a part resulting in the alcohol causing you to effectively act out of character."
Mr Simon Burch, defending, said: "She has shown regret and remorse." She has taken action to address and consequences of a life time of turmoil and abuse.""
For wounding, Jones was jailed for 28 months. There was no order made for costs or compensation.