When I was young I was madly in love my my first girlfriend. We had a very unhealthy relationship and after she dumped me and cheated on me I went insane. Among other things I signed into her email, facebook, and myspace, because I knew the passwords she always used and I discovered all her dirty secrets and that she had signed up for a dozen dating site profiles, which of coarse I also logged into.
I had tried just about every dating site out there as well but I always barely got any messages at all. When I logged on to hers I was amazed at the amount of emails she got. I read through every one. There must have been like 100 or more of them. Seeing her flirt and tell them what she was looking for, sometimes sending sexy pictures or ending in the exchange of a phone number sent me even deeper into a craze. So I changed all her profile info to say things like "I'm a bulimic, cheating, whore" and things like that. But that wasn't enough for me.
I also have set up profiles over the years on adult sites using some nudes she sent me. Most of the time I would crop or block out her face and always take it down after a few days. After a while it became more just exciting to pose as the girl who broke my heart and see all the responses than it was about revenge.
Even though its been about 6 or 7 years and I'm happily engaged to a woman I love I still get the compulsion to do this. I don't think I'll ever get 100% over her though. It still enters my mind a lot how much hurt I was in during that period of my life.