Madhu (25) has confessed to poisoning her children Abhishek (9), Guddu (7) and Suraj (5) at her father's residence on September 18, Inspector Civil Lines Satish Kumar told reporters.
She had been staying with her father since her divorce four years back, he said.
The three children were found dead in the house on September 18.
Initial investigations point out that Madhu had an affair with one Pratik, who also belongs to the same area, he said adding, she did not want to disclose it to him that she a divorcee and had three children.
Fearing that her past may create a problem in continuing relation with Pratik, she poisoned her three children to death, Kumar said.