My wife has a 13 yr old son who doesn't want to have a serious relationship with her. How can she handle it?

She was separated from him years ago by her controlling mother. She has spent the past eight or nine years brainwashing him and messing up his head. Grandma is a social worker and psychotherapist who feels vindicated by turning him against his mother. My wife is truly a sweet person with a strong heart, but her son can't see that. He won't listen to her, won't respect her, doesn't even want to talk to her and tell her how he's doing. We fought for three years to get custody of him, and were close, when he turned on us and treated his mother viciously. He only likes to pander to people's feelings and is very insincere with anybody who cares about him. It's a defense mechanism he's built up. Anyway, my wife hasn't spoken to her son in over two months, and doesn't really want to. What will help my wife at this point? Should she try to talk to him, or is she setting herself for more heartache? Should she never speak to him? What is best for her at this point? Serious only!