I hate my stepmom, what do i do?

i'm 16 and she is almost 25. and my dads 41. i used to be really close to my dad until she came along when i was 10...ever since my dad doesnt just spend time with his kids he ALWAYS ALWAYS ALWAYS has to be with her. she is alwayyyssss stuck up her ***. all the time. she isnt a good mother to her toddlers (my half sisters) and she bitches all the time. i just do not like her at all. my dad says me not liking her is why we dont get a long at all anymore. i try to be nice but i cant. i just wish she wouldnt have anything to do with me. what do i do?