The Secrets We Keep (en Inglés) - Angela L Keith

At Marshall Academy, you're either part of the elite, living in luxury, or you're like eighteen-year-old Margo Adams, a transfer student on an Alumni Scholarship, from a part of town known as "felony flats."
The only things that make the school tolerable are running, and her loyal friends who've never cared about her socioeconomic status. But Margo hasn't been completely honest with them about her life before transferring, and a school assignment is about to force her to come clean.
Further complicating matters, Margo's fallen for the most popular boy in school, and tries to keep the relationship on the down-low, afraid it will upset the status quo. As keeping yet another secret from her friends becomes strenuous, she'll have to decide which secrets are actually worth keeping, and how to open herself up without being crushed by her own pride.