Sibling rivalry I guess. Someone should sit your sister down and explain you are special people to each other and your relationship will last your lifetimes so do not be evil to you. What a shame. If that is love it is not worth having IMHO. Sibling rivalry sucks! Do not put up with it - tell her to be a nice sister or stop being anything to you.
is she an older sister and are you a teenager? older sister/brothers can be like that. They do love you they just like being as*holes to you as well.