She treats everyone like crap?

I've been here be fore I told my pops what I thought and l stayed out of the way and let him see for his self that his girlfriend was a bitch and needed to go and she did. Don't fight with her let thing work them self out.

talk to your dad about it and tell him how you feel, get him to talk to her about being more polite, have arguements ready with examples, if you an't provide proof it'll be a waste of time. if he choose's her over you then there's a much deeper problem that needs to be fixed

what the background of this girl, college education, good job, age.

Tell him how you feel about her and how she treats people in your eyes. if he's not willing to give her up or even defends her then you need to talk to her! It's a hard situation for parents to be in on this matter. You don't want to hurt your child but yet you want to have your own relationship with another adult. But if you have to talk to her tell her you don't like how she treats you and since your both apart of his life that some mutual lines have to be drawn and met.

You and your dad need a serious talk, daughter to father only. My and my step-mom had severe issues, as did my sister and her. We finally told him one day, and he told her that his kids were more important to him. He had no idea what was causing all the tension and ill-feelings because we never broadcast it in front of him. That's what you are doing, hiding it and letting the tension come out other ways, resulting in a lot of fighting.

I promise, sit down and tell him. He might not come around at first, might believe you are just being difficult. But eventually he'll see it now that the idea is planted in his brain. He'll be looking for signs, etc. that she doesn't like you and vice versa.

I would feel horrible. I think you should tell your dad your opinions about her, SECRETLY. You know, in a coffee shop or something. You should ask your dad "Don't you feel like a servant?" I mean your dad has a LIFE. He should try to spend it joyfully. Not getting bossed around! I have a saying called "Life is a work of art, you got to paint it colorful." Your dad's like is a work of art. He has to paint it colorful and enjoy it. I wish you luck. :)