How do i handle my dads girlfriend?

so I've been living with my dad and his girlfriend(her children as well) for about 3 years now and its starting to go down hill the longer theyve been around. My dad does not parent his girlfriends children, but she feels like she can parent me. I have...

over and over explained that she is not my mother and that if something needs to be done, my dad needs to parent me. but then she gets mad at me and throws a tantrum.. also things are not equal in the household. Her children always get the better advantage...and its not like there perfect little angels. She also minipulates my dad and I feel like its destroying my relationship with my father...how do I handle this situation??

One thing you need to understand first and foremost - you are living in their house, and regardless of the fact that your father has chosen not to parent her children, does not mean that your step-mother (that's what she is) does not have any right to parent you. She is a guardian to you and is legally bound to look out for your well-being.

As for fairness - forget about it, it will never happen. You can't go through life being bitter and envious because her children are treated better than you are - it's moot (having 2 step-sisters myself, I know all too well).

The best thing you can do is to give up your expectations and what you think should be going on in that house and just deal with it until you're old enough to start deciding for yourself. Sure, things in the house are unfair and it's making you angry - that's life, suck it up and be grateful you don't have to endure worse.

That's a tough one,have an alone talk with her tell her that there is only one parent in the house that can parent and if she can't deal with it,tough luck for her,she has to deal with what YOU want. As for her children,simply barge in every time you see them getting something you don't have and if their mom says back off or even them,tell them,it's your house to and you deserve a part of it,if they go to their mom,tell her the same thing and the same goes for your dad.

well if I were you I would get you dad and tell him about what is happining and then talk to his girlfriend and if she doesn't listen then to you then don't listen to her

You need to talk to your dad about how you feel. Regardless of whether your father's girlfriend is your birth mother, she is an adult and you are to respect her. She will probably respect you back.

I am in a similiar situation and it helps me to think Hey, in just a year or two I can move out!

You need to talk to your dad and tell him all about it.
Maybe try to respect your dad's girlfriend more?
If she parents you well, why not just accept it?