How do i tell her off?

there's this girl in my cl and she DRIVES ME NUTS!!! she always tries to get me in trouble and she yells at me and steals alot of my things and shes just so UGHHHHHH some of you might no aht i mean,, (im in 5th grade btw) And were going to the KNOX. zoo tomorrow. I need to find some way to tell her off so she will leave me alone for the whole trip. and also make it so we don't get in that much trouble. just help me and idc if theres bad words in it cause i can always replace them .. thx and also please DON"T SUGGEST that i tell an adult cause ive already tried that and she has lied outta it and i always got in trouble thxx and any answer counts (kinda)