I'm basically going to tell my sister to fuck off
Why would you say that to your sister?
She was spreading around rumors about me.
It's a shame that your sister is spreading rumors, as that must hurt and make you feel betrayed. Rather than telling her off, I think you should rationally confront her and let her know how her actions are harmful to you and how you feel.
It's making me so tired. How can I be positive and good?
I bet your sister will come to the realization that she's doing wrong if you talk to her. Don't be so hopeless about it. These kinds of sibling fights are common everywhere.