The accused Dhruvkant Thakur surrendered before police and was subsequently arrested for the alleged crime that took place early on Wednesday.
The victims were identified as Dhruv's 24-year-old wife Sushmita and her lover Ajaykumar Singh (27), police said adding that after the murder, the accused had also tried to kill himself.
According to police, Dhruvkumar and Sushmita had been living separately since the past few months and Sushmita had handed over the divorce papers to him through an advocate.
"The incident took place at a flat in sector 19 of Kamothe in Navi Mumbai, where three of them were present. After an argument with Ajay, Dhruvkant lost his temper and slit Ajay's throat with a knife killing him on the spot and smothered his wife with a pillow," a police officer said.
"After the double murder, Dhruv came down at the entrance of the apartment around 6 am (on Wednesday) holding the blood-stained knife and clothes.
The watchman of the building was aghast to see Dhruvkant in such a condition," he added. The accused himself told the watchman to inform the police about the incident, following which the police were alerted about it.
The accused surrendered before police and confessed about his crime, the officer said. "Before descending the building, Dhruv had tried to commit suicide by hanging himself from the ceiling fan inside the flat, although he did not succeed in it," said police.
The accused has been booked under section 302 (murder) of IPC and further investigation into the case is on.