I don't know how to handle this. Need advice.?

So ive been through this, but instead of being the step mom, i am the step daughter, at first i was really liking my step mom but then for somereason as i was growing up i felt like she had no right to tell me what i could and could not do, my thought prosses was "shes not my mom, you can only have one mom" and it hurt my step mom alot, But she did the one thing you shouldnt do, she gave up on me and started acting harsh towards me, now see that made everything worse because we would end up fighting every night. so the one peice of advise i can give you is dont give up.