Before going on holiday sister told parents she was tired and not coping with kids (has PND). Goes on holiday. No text saying she had arrived safely. Parents worrying all week. She gets back and phones up - dad is emotional and asks why she didn't have the decency to send a quick text. She takes it personally and conversation goes from bad to worse. She is now expecting a written apology from him but he doesn't think he needs to apologize. Any advice?