My Mom's the problem

Every Sunday something just goes wrong with her. She just gives everyone the cold shoulder and waits for us to start getting sad too. I don't know what's wrong with her! And it's not like it's just a monthly thing, it happens every week. She cusses out at us and teaches my little brother all these horrible words. She complains that we don't help clean up, but I help all the time. And when I ask her if I can do something, she just says a bad word and says, "I don't care!" But she's fine the rest of the week! What is happening? Why did I have to be in this family? I wish every day that I cross the street that maybe a driver is going mad and heading straight for me.