The Sahibabad police said the incident took place on the night of June 7.
Vimal Kumar (35) was a neighbour of the woman, a resident of the Harsh Vihar area. The woman is a divorcee and had an affair with the victim, the police said.
On the night of July 7, the woman's brothers caught the couple in a compromising position in her room.
They dragged him outside their house and thrashed him. Kumar died on the spot. The brothers and one of their friends dumped the body in a drain near the Delhi-UP border, Superintendent of Police (city) Akash Tomar told reporters.
On Tuesday night, they arrested the brother duo and sent them to jail, the officer said.
Disclaimer: No Business Standard Journalist was involved in creation of this content