A man accused of killing his wife in Guelph, Ont. has admitted to hitting her over the head with a shovel, encasing her body in concrete and living with his mistress while he covered up the crime for nearly a year.

Stephan Dietrich, 45, pleaded guilty to second-degree murder Thursday in the death of his wife Seble Dietrich, who was well-known in the community as “Mimi.”

“It was a tough day for him, it took a long time to come to this decision,” Gregory Leslie, Dietrich’s lawyer, told CTV Kitchener. “We had to go through the case very thoroughly.”

The 40-year-old woman’s disappearance in 2014 was not originally deemed suspicious, but Dietrich was charged with her murder nearly a year later.

Dietrich told the court on Thursday he and Mimi were fighting over a phone bill when he hit her over the head five times with a shovel and put her body in concrete. He then told their three children that Mimi did not love them anymore and had left for good.

According to an agreed statement of facts, Dietrich sent a letter to a friend where he pretended to be Mimi and wrote: “I’m gone and will not be back. I have committed adultery and I am now pregnant. Help my husband to find a woman who is better than me.”

Court also heard that in the months following Mimi’s death, Dietrich’s mistress moved in with the family in Guelph.

Dietrich will be sentenced on Nov. 22. Both the Crown and the defence are asking for a life sentence without eligibility for parole for 22 years.

Leslie said Dietrich could be deported to Germany to serve his sentence.

“That is up to Germany, I have no idea what their intentions would be, but that’s quite a ways down the road,” he said.

With a report from CTV Kitchener’s Nicole Lampa