Silence by Natasha Preston

Eleven years Oakley has been silent, hiding a truth that would rip her world apart. Refusing to communicate beyond a few physical actions, Oakley remains in her own world. Cole is her only friend, he fights for her, protects her, but as they grow closer together, their relationship gets put to the test. When Oakley is forced to face someone from her past, can she hold her secret in any longer?