Is it okay that I ripped up my little brother's science book?
Are you joking? Why would you rip up his book?
He's little prick who hates to share.
Tension between siblings is inevitable. But, it is very wrong to destroy another's property and that book is the property of his school.
I'm already wishing I'd said sorry.
It sounds like you regret what you did and are ready to apologize and that takes a big person. You are the older brother, he'll learn from you in both good and bad ways. Stepping up and apologizing for what you did will also teach him proper behavior.