I don't want a relationship with my estranged sister.
Is there something about your sister you don't like?
She's constantly nagging me and whining about things.
It can be difficult sometimes dealing with family members, but it's important to try your best to be there for them. Especially since your sister was estranged before, you should try to welcome her back. Be patient and understanding with her.
She texted me while I was busy. She ruined my plans and I hate her for it.
It sounds like a bit of an overreaction to hate her for simply texting you while you were busy. If you were busy, you could have simply responded to the text when you had more free time. I think your relationship would be better if you just communicated better with your sister.