As others have commented, there is always another side to a story. If your father leaves your family to live with someone else, then expects you to embrace him abandoning you, then what do you expect? Yes, rudeness is unacceptable, but any parent who abandons their kids must take the consequences that goes with that decision. Did he make any effort to see them as kids? What goes around, comes around, especially later when the kids grow up. Inheritance is not a fee for service. The single mum probably has her own parents to see to and inherit from. Sounds like double neglect to me.