Help my stepmom is a nutter !

My mother died when I was 13 years old, my dad found a new partner soon after and they have been together for nearly 7 years. My dad was a brilliant parent and gave me the best childhood he could, he waited for me to finish high school before moving in with his girlfriend.

So when I started sixth form we moved about 15 miles away to a new city where we had a new house, a new family and a new way of life. We’ve currently lived in this house with my dad, his girlfriend and her daughter for nearly 3 years, part of me loves this new city as I’ve met some brilliant new friends and an amazing boyfriend.

But, part of me hates it because my dads girlfriend is a COMPLETE and UTTER NIGHTMARE. At first she made sly digs towards me about how I would do things differently and complain to my dad about things he would let me do and my friends coming over when her daughter is allowed everything she wants. (Btw her daughter is 4 years younger than me) Over the past year it turned to her accusing me of all sorts of ridiculous things. E.g. like sabotaging her washing???? I mean get a grip!!

I go to uni so I’m only at home during holidays but even then she can’t stand me. Luckily my dad always sticks up for me but this past week she has flipped out yet again over some trivial disagreement. She took me into a room to lecture me that girls who mothers die should like their fathers new partners just to please their dads. Then she blocked the door so I couldn’t leave, I don’t really like it went she talks about my mum but she knows that.

Some people think she is jealous of the relationship that my father and I have

however, I just think she’s just tapped in the head !!!!

Any advice???