That is ridiculous that you have to hide in your own house. Maybe your mother just goes out with this guy because she wants to feel miserable. It gives her an excuse to break down and run over and annoy you so she doesn't have to deal with her problems that are manufactured by herself. But remember that if someone stays at your house long enough according to the law they are legally residents, and it becomes much harder to kick them out. Hopefully for you she will leave tuesday, if not, I say ask nicely once and if that does not do the trick get the police to show up and walk her out. And you are fine.