Has a book ever been written in second person? If so, what is it?
Yes, quite a few have been written in second person.
Here is an example: In second person, you only hear the narrator speak, think, and understand. The narrator may talk to the audiance, and they often address you.
"She hears a voice. 'Abagail, you are not meant to be here.' Max is right or course, how could he not be? You gape at the intensity of their love for one another. She knows she isn't supposed to be here, but she just cannot stay away! And of course, she loves him. Yes, she does. You feel your chest ache, as their love grows bright beyond the light of the sun."