I agree what everyone is saying here. As a woman, personally, if I become exclusive with someone there is NO NEED to be on a dating site, you know? Facebook and AOL chat and some of the other social media sites aren't bad because it's just about making friends. I know my boyfriend had his eharmony profile up for several months after we became exclusive, but he wasn't out meeting women. And even if he was I never "caught" him in a lie like you have.

That is betrayal my friend, of your trust. This doesn't sound like someone who wants to be in a serious relationship with you like you want. Don't keep hurting yourself, you deserve to be happy!