The woman and the victim were said to have become close friends over a period of time and used to frequent each other's house before the incident, police said.
They said the woman last month forced the victim to have sex with her husband while she watched it. She had allegedly threatened her friend that her husband would be killed if she did not do so.
A fortnight later on August 10, the woman allegedly pressured the victim to repeat the act with her husband, police said.
The victim then brought this to the notice of her husband and both approached police.
Police today said the woman and her husband have been arrested.