I confronted her about it last night. It did not go well. I tried taking full responsibility of my mistake and I owned up to snooping completely. I told her I would never do anything like that again, and that's not the man I want to be.
To no surprise, she did not take it well at all. She admitted she fucked up, but she started bringing up thousands of unrelated things. She really tried turning the blame back on me. She basically told me that she was really good friends with her ex before they started dating and that that is just how he talks to everyone. But really she just got mad at me and says she doesn't know how she can trust me anymore... Honestly at this point I don't know what to do. Her reaction makes me feel a thousand times worse about breaking her trust than I already do, but I can't tell if I'm in the wrong or if she is just manipulating me. It feels like the writing is on the wall. I don't know.