Your father is sounds like the reasonable one who can explain to your mother that, as the mother, she needs to stop this behavior now. She is driving your family away and she can only end up hurting herself. So, if she wants to see your family in the future, she needs to get over it. Period. And all the siblings need to reinforce it. That is the message the rest of the family needs to convey to her. Sometimes people grow old without ever growing up.
