United News International (UNI) – The Colorado man charged with killing his pregnant wife and two children reportedly has admitted to killing his wife in a rage, but he claims, only after he saw her kill their two little girls.

According to court documents released Aug. 20, Christopher Watts has admitted to having an affair.

He reportedly told his wife, Shannan, he wanted a separation.

Watts says he later saw her strangling 3-year-old Celeste in the baby monitor and when he got to the room, 4-year-old Bella was already blue lying on the bed.

Authorities say Watts confessed to burying his wife in a shallow grave near two oil tanks outside of Denver and dumping his daughters inside the tanks.

Police drones found a sheet from the couple’s home in the field near the tanks where the bodies were found.

Watts was formally charged with five counts of first-degree murder, one count of unlawful termination of a pregnancy and three counts of tampering with a deceased human body.