I'm pretty sure it didn't happen. If you think about it, DeSimone was scared of his own shadow. He wouldn't even collect protection money from bookmakers because he was afraid they would run to the police. He only went out at night after he found out Joe Bananas was after him...doesn't seem like the kind of guy to abuse someone so horribly. I tend to believe a game of telephone was being played. Momo's wife slept around which became Momo's wife slept with DeSimone which became Momo's wife was raped DeSimone...

But really, who knows. Maybe the answer is an old FBI file.