Sounds like your dad is a dick, and his new girlfriend is a spoiled brat. It'll be tough, but you're going to have to make your dad see sense, before this gets worse.

I would have beat that girl senseless

This is where you take the notebook and throw it in a lake. Or as the wiener if the computer, call the police and press charges. Do your dad a favor.

Either press charges for vandalism/property destruction or sell her notebook to at least cover some of the damage costs.

Umm what is your dad a total wuss kick that spoiled brats ass or call the cops on her because that's uncalled for and tell your mom if you can 😊

Is it broken?

Sounds like the plot line to a porno. “Time to teach my future step sister a lesson” lol still sucks though.

Press charges, maybe just maybe she’ll see the light.

liar

So you have a new notebook