The dad's problem fits neatly into the "you did this to yourself" box, and is the direct consequence of his actions. There is no reconciliation possible here. The dad has had sixteen years to get rid of his bigotry. That's more than enough time, and his failure to do so is what led to his estrangement.

I wish the best for the son and his husband. It can be stressful when a someone you've cut off keeps intruding on your life.