Dude if you fuck her and then throw the print outs in her face, tape that shit. That would be the funniest shit I've ever seen. But seriously fuck privacy bullshit. If you and her have been together for almost a year then she wouldn't care if you read what she wrote unless it was something that she knew she shouldn't have done. I would go seperate ways. As far as how I would handle it, I would show her the evidence either after sex or without no sex.