Hard question. How do you use e-mail? Through microsoft outlook? Do you have MSN (if you altered it, it may change in your user details, I'm not sure, so if he knows your user name, he could get it from info if you allow it to be shown). Really, the question has to be asked, if you changed your e-mail and didn't give it to anybody, why have e-mail? If you are absolutely sure you didn't give it to ANYBODY, you have cause to wonder, but if you did, then ask ANYBODY. Or ask yourself if ANYBODY has cause to betray. If he has access to your computer and you use a web based e-mail like hotmail, when you sign in, if cookies are enabled, it will display the last typed in e-mail address in the address field when you next go to the hotmail website on that same computer.
[email protected] if you want to discuss it more (I'm no expert, but I know my share).