I found another womans phone number in my man's phone book?

Well sweetie you know how the old saying goes, Seek and ye shall find. I don't think it was cool that you went through his belongings, now your upset at what you found. People have a way of revealing themselves to us without us having to go snooping, I am sorry that your hurt though. All in all though you need to talk to your man about what you did, and what you found. Naturally he's going to want to know why you did it? So just be a woman and speak your truth, if he really loves you, then you two will move p this. But in the future don't go looking if you don't want to find. Good luck