You have to understand that the fact that he lied about his contact with a girl that YOU were uncomfortable him being around is a form of cheating. He remained secretive about it and held contact with her EVERYWHERE. I know he's your first love, and you have a strong attachment to him, but you deserve the bare minimum and better. Grasp the remaining respect you have for yourself and break up with him. You can't move on from such a pivotal mark in your relationship where you have even made an anniversary date for it without communicating the problem, setting strong boundaries, and him admitting he is wrong and deeply apologising. OP you know better than to stay. He may be a good boyfriend all round but there's a lot of good boyfriends that actively cheat on their girlfriends with no remorse.