Performative Masculinity - The Bradford McKinley Chronicles, #3

Emily Wilson has a secret: she's a girl. No one outside of her family knows. And no one outside her family must know, not until she's ready to come out to the world at large. So at school, she puts on an act: she's "Wilson, " the hoodie-wearing, grumpy, sullen, unapproachable boy, who beats up bullies but otherwise minds his own business and doesn't talk to anyone. And it's been fine so far. The ending line is in sight: in a few months, the school year will be over, and she'll be able to come out. But then one day, when she's out and about, dressed as a girl, Emily has a chance encounter with Josh Woods, one of the people from her school she most dislikes.
Faced with the possibility of being outed, Emily pleads with Josh not to reveal her secret. And his response surprises her: he won't tell. Because he has a secret, too.