I Dont Understand People

I don't get it. (I'm visiting my family for the holidays) So because me and my father want to relax my mother says she has a right to insult us. She wanted to go out and have fun, which she did, though by herself. My father wants to relax because he's had a long day at work (and he has two jobs). I'm not feeling well so I didn't want to take it out on her by being nasty and stayed alone so that I couldn't be rude to anyone. But she still believes she has a right to insult us. She just said something very appalling to my father. I can understand that she is upset but that doesn't justify insulting us. I can't believe this behavior is coming from a 57-year-old.