The couple already lived separately, as the woman, named only as Subasini, was in the process of leaving Varo V. because of his violent, drunken behaviour, the Bild newspaper reported on Wednesday.
The 39-year-old was taking out the rubbish outside her apartment building when her 42-year-old husband approached her, ostensibly to pick up a telephone card. But the couple got into a row because he had been drinking, the court in the western town of Bochum heard.
At that point, Varo V. produced a steak knife and slashed at her, and she held up the bin bag to protect herself. The knife sliced through the plastic bag and a banana skin fell out onto the ground.
When the man tried to attack her again, he reportedly slipped on the peel, and the woman used the opportunity to escape into the building.
The accused admitted the attack. "There was a row because I was drunk again," he told the court.
"Then we scuffled because I wanted the card. Then the knife fell out of my pocket. I got angry and stabbed into the bag. I can't remember any more."
His lawyer Martin Gentz told the newspaper, "My client regrets the incident. He wanted his wife back, was in despair, and didn't know what to do next."