Patience Shiri said she found out that Angela Katsande was her husband's girlfriend after she sent love messages to the man's cellphone.
This emerged at the Harare civil court where Katsande made a peace order application against Shiri.
Katsande told the court that Shiri has become a nuisance after she found out about the adulterous relationship.
"She calls me in the middle of the night demanding that we should talk.
"This woman sends me insulting text messages and is now directing my life by telling me what to do, when and how," she said.
Katsande told the court that she knew Shiri's husband since they were children and were the best of friends after attending the same schools from primary to high school.
"He told me that he had financial problems and I offered to help him since we are friends.
"This woman is actually his second wife because his first wife stays in Kuwadzana.
"Shiri and this man have marital problems and have taken each other to the High Court," she said.
Responding to the allegations, Shiri told the court that she knew Katsande when she was introduced to her as a sister-in-law at the funeral of her child.
The court heard that from that time Shiri started regarding Katsande as family and she would frequently visit her home.
"One day I found a message from her in my husband's phone saying she missed him terribly.
"I then confronted her to ask why she sent her brother such an intimate message and I got the shock of my life," she said.
Katsande, who is married with four children, revealed to Shiri that her husband was proposing love to her.
"She also told me that next time I should not confront my husband's girlfriend because the moment I confronted her, her longing for my husband increased," she said.
She added that her husband told her that she was interested in having a love affair with Katsande in order to ease their financial problems.
Katsande went on to buy the family a car, the court heard. Katsande produced text messages as evidence, but magistrate Ms Tatenda Manhanzva dismissed them as not offensive.
The matter was postponed to tomorrow to allow Katsande to get a printout from the service provider to substantiate her allegations.