I'm going to tell my sister she was a cold hearted bitch
What did your sister do?
My sister was a cold hearted bitch just because she wanted to have a nice relationship with my mother.
You shouldn't call you siblings names just because they're doing something you dislike. Especially if what they're doing is harmless. You're just going to create needless drama within your family.
My sister is worthless, I don't care what she feels.
That's uncalled for. It is normal for siblings to be annoyed at each other but please keep the peace. If you yell she might yell and tell you something similar and since you started it you might be the one in trouble.