Compulsive Liars...... Do they ever realize their mistakes?

I have caught my bf of 6 yrs cheating on me.... no matter what proof i gave him there was always some excuse made. I put up with this crap for 8 months and have finally given up hope that he will ever change. He finally admitted to me after all this time that no i was not crazy but that he was cheating. He apologized and told me he was turning over a new leaf. Not only that he told me that he has told her its over..... BUT... i have his vm pword and have been checking, (rightfully so) and it seems to me that they are still together...... i have decided to be stong and brave and leave him. I am deeply hurt that he is still lying.... doest he think he will get away with it again? Do ppl like this ever get what they deserve? I cant rest until i know he has been punised for being a cheater and lyer. Do you belive in Karma?