Bad home situation continued

Hello so my family problem hasn't resolved. My brother's wife and her kids continue to live with us. But i feel this is so unfair-every time my brother stuffs up financially, etc she expects my parents to look after her. I don't understand why she wont leave; i mean no one should force others to live with another family should they? They ask too much of a favour like this and still continue to act like its their house. They don't seem to understand the effect it must have on our daily lives. I can't even leave my room anymore. Its been 9 months and i have tolerated it enough... i've become depressed, trapped and angry. I'm just curious is she doing the right thing??