Timothy Havens, 38, revealed to the police that he was reaching for something on the bedside table when the pistol went off, hitting his estranged wife Carolyn in the chest, reports US news channel WLWT.
"[The gun was] right beside the bed. I picked it up and put it off to the side. We were having sex and it went off," the Sydney Morning Herald quoted the man, as telling on the emergency call he made soon after his wife was shot.
Havens was arrested after the police found out that his wife had a civil protection order against him.
He is also said to have spent 60 days in jail for assaulting his wife, WLWT said.