I hope it's not poor etiquette to jump in with a first post of this nature.

A little background:

I am a 29 year old man who had never dated at all until I met my fiance in early 2012. I have always been shy and suffered from depression, anxiety and poor self-esteem. In the years and months leading up to meeting her I had done a lot in terms of self-improvement and felt like I was finally ready to try to date people. To that point my romantic interactions had consisted of one kiss and dates I could count on one hand. I joined a dating site and through a stroke of luck the second woman on the site turned out to be amazing and actually liked me in return. She knew from the beginning I had never dated and she patiently and lovingly helped me discover romance, sex and love for the first time, culminating in our recent engagement. I love her with all my heart and have absolutely no doubt I want to spend my life with her and that we make a great team. I know she loves me and I love her. It took me a while to come around to it, but I know this is true.

She had been in one long-term relationship before and had had a handful of more casual sexual partners and short-term relationships. She has indicated that some of her past sexual encounters involved a combination of loneliness and alcohol. For a woman of 35 I would not classify her past as promiscuous by any means--she had had a total of 5 sexual partners before me. She herself came late to dating and sex and didn't have her first sexual experience until she was 25.

I feel like she and I have a great sex life. We have sex 4-5 times in an average week and I feel like the sex we have now is passionate and fulfilling.

But I am still haunted by her past sexual experience and her ex-boyfriend. I sometimes get obsessed with thoughts of her having sex with other men. The worst manifestation of this obsession I have is that I have invaded her privacy by reading journals and e-mails from her past. I feel awful about this, but it is like a compulsion I have trouble controlling. I feel like I have profoundly violated her trust in me and I highly doubt she would ever pry into my private information. Every time I have done this I have come across something I find difficult, including graphic descriptions of sex with other men. Every time I do it I promise I will not look again, but there is more info out there and it is easily accessible to me, and inevitably I lose my self-control and go back for more. her archive e-mail is available on a portable decide she owns but shares freely with me and she has journals and other mementos in a box in plain view in her bedroom. I have also looked in drawers and found things like condoms and sex lube that we have never used, and I found these a bit distressing. I also come across photos from her past relationship (not necessarily as a result of snooping) or hear her mention in passing "I went to that place with my ex once" and my thoughts go into a downward spiral obsessing over her time with him and with other men. She knows this is difficult for me and she always reassures me "He's in the past for a reason. You offer me so much more than he ever did. I love you and not him." And I believe her, but it does not change my thoughts.

I know this is my problem, not hers. I do not fault her for exploring her sexuality because I would have done the same thing given the opportunity. I do not fault her for having a past relationship before me. It is up to me to learn to manage my own emotions and come to terms with it. She has done everything I could possibly expect of her to make me feel loved and secure. I know that her past has made her the woman that I am in love with. I know that her past experiences led her to me and mine to her, but it just nags and eats at me (because I have let it do so). I need to get over it not only for my own good but because I owe it to her.

So my question is two fold:

How can I truly accept her past and not let the insecurity I feel interfere with our relationship?

And...

How can I conquer my compulsion to invade her privacy?