My father's girlfriend is an idiot - Update

When my father told me he was in a serious relationship for a month I said "ok" and that's it; he's divorced, so he has all the right in the world to date someone again.

I didn't meet her yet, but after some things I don't even want to. Not anymore.

Fisrt: when my cousin was robbed, she went to my aunt's house with my father to comfort her and everything I didn't like that much because this is a family matter and she's not family, but I said nothing because I didn't want to cause any confusion.

The last drop was: because of her my mother can't come to our house to sleep here. Come on! My mother has right to visitations and she owns 50% of the house, so she can come here when she wants.

When the divorce came out, the judge said my mother had the right to see my younger sister and that one weekend she would come to our house to see my sister and the other weekend my sister would go to her house. My father said after that my mother could come here anytime she wanted, not only in the weekends.

Now he got this girlfriend, everything changed. My mother can come here, but no to sleep over and my father is using the judge's decision as a fucking excuse to please his fucking girlfriend...a woman he has been dating for a month and he doesn't want to admit that. Really? My father should grow some balls and admit that he took this stupid decision because of the jealousy of that woman. And he said because she's conservative and he worries that people could talk behind his back about having two women - his ex-wife and his girlfriend - coming to our house. I told my father he shouldn't give a fuck about what other people think. Let them think what they want.

I don't give a rat's ass if my father gets a girlfriend; what I don't accept is him letting her meddle in our family's business.

My father is planning to take her here to meet me and my sister. I don't want meet her. If I see her I won't be rude or anything but since I can't hide when I don't like someone. I would be with a frown for the entire time she will spend here, I won't barely talk to her and - obviously - my father is going to notice and this won't end well for me.

In a nutshell: his girlfriend is a cunt.

Now, I don't know what excuse I can come up with when my father tells me his girlfriend is coming to meet me and my sister.

Update: The result of all this is: my mother doesn't want to come to our house anymore and she doesn't want my sister to sleep in her house. This decision of her is going to bring me a lot of trouble. My sister has special needs (she is autistic and she depends on us for everything) and someone have to take care of her.

It was all doing fine after I got a job; when my father had to go to work she stayed at my mother's. Now my mother had a fit over  my father's decision and she told she's not going to take my sister at her house to sleep over.

She said if my father wants someone to take care of my sister that he hires a housekeeper/nanny for that (which he probably won't do it). Now I fear having to quit my job (which took forever to get) to take care of my sister.

I'm really angry at both of them. None of the two wants to give. They only think about themselves and they don't give a damn about what their decisions will affect others (in this case my sister and me); and they have the nerve to call me selfish.

My mother said she was happy that I finally got a job and that she would do anything to help me so I won't lose it. If that was true she would swallow her stupid pride and keep her word. But she didn't. She promised she would help and now she backed down...again. I don't know why I even bother to trust in those two. They are willing to help me as long as it doesn't interfere with them. I don't know why I bother to trust them. Every time they needed my help I had to help them; I made sacrifices for them; I didn't do the things I wanted to do their obligation (taking care of my sister) and I wasn't even allowed to say"no". If I did they would make a scandal.

My mother says she will only accept my sister back when my father sells the house. Really? I don't have the luxury of waiting the house to be sold! If they put the house for sale who knows when the house is going to be sold!

I don't know what to do! I don't want to lose my job! I can't be a housekeeper/nanny again! If this happens, I will go crazy!