I absolutely despise my older sister
Why do you hate your older sister?
I can't stand her anymore. I was just a kid when she used to bully me into submission
Your sister was not a good role model for you by being a bully to your back then, I feel your pain. Being mature and talking things out now can have a positive reaction with you both, otherwise things will never change between the two of you. Expect to have more fun when the two of you aim for maturity and getting along.
I can't be mature at the moment. I really want to hurt her. It's all her fault too.
You should never despise your sister so much that you want to hurt her. It's important to get along with siblings because you're going to be dealing with them a lot in your life.