If you just don't talk to him when he calls, he'll get bored and stop calling. Any little bit of conversation you give him encourages him to keep calling.

Making contact with his wife is actually a way of you getting more deeply involved with him. I wouldn't do that. Don't imagine that you would be helping his wife by contacting her. It may be that she avoids knowing what she prefers not to know. That's her right. Stay out of it. Otherwise you are just spinning this into a bigger drama.

This guy seeks attention from women. Give him none, and he will tire of trying to get it from you. There are plenty of other women out there for him to seduce, and he will find one.