The deceased have been identified as Neetu (30), and her children Tanishk (5) and Reyan (2).
Police found purported scribbles over the wall of her room where she has accused her husband Rahul Thakur of having an illicit relationship with another woman which led her to take the extreme step.
The incident came to light yesterday around 9 pm when Rahul returned from work.
Rahul and Neetu had got married about six years ago. Rahul works as a software engineer with a private firm in Gurgaon and lives at the Shakarpur's Sunder Block with his wife Neetu, mother Maya Devi, elder brother Rajesh Thakur, his wife Shailja and their two children.
He raised an alarm and broke open the door to find his two children lying on the floor with froath oozing out from their mouths. The three were rushed to Lal Bahadur Shastri (LBS) hospital where the trio was declared dead.
The woman's family has alleged that Rahul had stopped giving money to Neetu after she confronted him of his extra marital affair. She had even taken up a job to make ends meet and feed her children.
Neighbours told police that they often heard arguments between the couple during nights. Neetu's family also alleged that the handwriting on the wall, which the cops are taking as a suicide note, is not hers.
Police is investigating the case from all possible angles while an SDM enquiry has also been initiated into the matter.