I had the same deal with my ex except she would use different IM's and pretend to be someone else in hopes of getting things out of me. Then she'd stalk me on han (EVEN A ****ING YEAR LATER! , and emailed me for the next year and a half. I moved, changed my AIM and cell number.

Whatever you do, don't give in. All they want is to find out if they are doing better then you.