The 52-year-old man from Königswinter near Bonn said he and his wife had had yet another row in the bathroom on the morning of Valentine's Day, 2008.
She had shoved him when she got out of the shower because he had failed to answer a question, the Spiegel magazine reported he told the court.
He pushed her back and she slipped and fell, bashing herself so badly she started bleeding. She screamed and attacked him, when, he told the court, "something went click" and he grabbed her throat and squeezed until she died.
He told the court he had worked for up to 14 hours a day, and that his relationship with his wife was characterised by nagging and arguments - and that she often criticised him for not making enough time for their children. This was all exacerbated, he said, by money worries.
After concreting his wife's body into the cellar, he successfully convinced their children and family friends that she had simply left after a huge row. After a while he even married another woman.
It was only four years later when their daughter, by this time 21 years old, filed a missing person's report in 2012 - that the police launched an investigation.
When detectives started making moves to dig up his garden, the man told them everything and led them to the cellar where the body of his wife was found concreted into the wall.
The district court in Bonn on Monday convicted him of manslaughter and jailed him for eight years.