BF Trouble. Please help me?

Ok. I'm 14. I have an amazing boyfriend that i LOVE more than anyone could imagine. We've been going out for about 7 months. and i NEVER lie to him. I never hide things either. But today, I was messin around with my best friend, and he game me this book that my bf had written about his memories. and one of the stories in it was about his first crush. of course i read it, and the girl is one of my best friend, and it was in kindergarden so it's cool. im not jelous. i thought it was soo cute, but idk if i was supposed to read it. i dont want him to get mad at me, or anything. & on the first page of the book it said "This book is dedicated to [the teacher] and was so i could get things off of my shoulders without talking about it in public" and i want to tell him SO bad, but idk if i should. i think i should, i just dont want him to get mad at me. i didnt see the note about the public or anything untill AFTER i read it.do you think he'll b mad at me.should i tell him.should i have read it