I can't stand my dad's girlfriend.

  I just can't take her anymore. She's a fairly decent person and I know she's had a rough life, but I feel like she's taking all of her frustration out on the world (and me). It's really hard to be friendly and sympathetic to someone who barks orders at you and is mean to your family. She has helped me out a few times when I was in a jam and has given me some of her old stuff, but I don't want her around me.

 I become very sheepish and sort of passive-aggressive when I try to tell my dad about something I know is important to him, so I don't know how to tell him that I don't want her around me. He loves her and he can seem to tolerate some of the madness, but I shouldn't have to. She's not my mother (even if she was I wouldn't take this kind of treatment) and I don't know how long she's going to be around for.