I do feel for you. Your torturing yourself. I've done it to myself so many times. It's a negative thought pattern that can consume you. You need to be open with her about this. She must be understanding if she has stuck through this with you. Please talk to her so she can understand what's going on in your head and maybe help you through it. It's a problem that will occur with any relationship you have. I had guys lie and cheat and I was always able to catch them by checking emails and phones. In two years, my boyfriend has never lied to me once and I've tried to catch him doing "something" at least 20 times, maybe more. I hope you can get past this.