I hate my boyfriends step mom
Why don't you like his step mom?
It is her fault that I'm suffering so much she is just hateful.
I'm sorry you are feeling that way. People often don't live in harmony with their in-laws. It's best to try and find some common ground if you are going to be together for a long period of time.
I can't. I can never be nice to her even if I tried.
Well I recommend you at least try if you are stuck living with her. Or at least talk to her and tell her why you're upset with her.