Richard McAnulty will serve at least 25-years after pleading guilty to murder by abuse for his role in the death of Jeanette Marie Maples.
He testified that his wife, who received the death penalty would turn up the TV in the living room to cover up the sound of her beating Maples - and it didn't work.
"You could hear the whips," he said.
"It was horrifying. I didn't know what was going on. Her mom would have her strip naked and whip her."
He added: "I failed her. I failed her as a father. I didn't get help for her."