I like my bro's girl?

My brother is a senior at a different high school and i am a freshman. he is going out with a junior at my school and i think i am starting to like her. she is in my western civ cl because you can pick your cl in any order u want and my lunch an i don't know what to do. i think i like her and i no bro's before hoes but when i see her i sometimes can't look away.