Break up. No seriously, whatever you are trying to prove is irrelevant, your relationship is already beyond saving. Trust is the foundation of any healthy relationship. You don't trust him. Whether you are correct in doing so is entirely beside the point. The damage is already done in your mind. There'll always be nagging doubts or guilt. What are you trying to accomplish? If you find out there is something wrong your relationship is over. If you don't, you've just majorly violated the trust of your significant other, potentially causing a break-up as well. What is the perfect outcome here? You get in and they never find out? So secrets and backstabbing? That's how you want to proceed in the relationship even though it's exactly the thing that worries you about your significant other?
It's not worth it. Just admit it hasn't worked out the way you wanted to and move on. Spare yourself and your significant other the falling out and emotional void of a decaying relationship.
If you seriously want to progress with this relationship but you can't get over the e-mail thing, just suck it up and ask for access. Admit your weakness and hope for lenience.
