Any attention this guy gets from this will encourage more drama from him. He hasn't managed to move on with his life. So he's trying to squeeze himself into the middle of his wife's new life. He sounds mentally unbalanced to me.

Dealing with him is really your wife's resonsibility, not yours. I can understand her showing you the note and looking for you to be supportive. I agree with the posts further up that discourage giving this guy any response. Your wife must be really glad to be away from him.