The breakup was 10 years ago, and the daughter is an adult. She doesn't have to accept her new stepmother as family or even a friend, but she should at least be courteous. Instead, she's acting like a child and being incredibly rude and insensitive. Her lack of regard for the feelings of others, especially a handicapped man who may not understand why he is being ignored, could indicate a personality disorder, or just plain bitchiness.