Believe me, I understand the urge to want to check things. I haven't in soooo long and yet still in my dreams, I'm going through his cell phone! Yikes.
Here's how I stopped. I told myself that he is insane at the moment, actually not the person I know at all, so it doesn't matter what he's doing.
When they are in mlc, they do do a lot of things that are insane.
Each time you resist you create the habit that you won't check. Maybe make a deal with yourself, I will not check for 3 months at least. Then it's like you can put it off and trick your desire, however after 3 months...who knows..