Meh she'll get over it. Don't over dramatise this and allow it to become bigger than it is. she breached your trust reading your diary, I'd be very annoyed about that. Tell her you love her, tell her you are however entitled to have privacy, and discuss the issues that caused you to write them in the first place. this is a wonderful chance to get your relationship on a better footing, bit stop obsessing over it, and don't let it drag out and become a massive drama.