Infidelity Support Group
Any relationship in which one partner engages willfully in sexual relations with another outside of the partnership is considered to have experienced infidelity. This breach of trust is often traumatizing for the faithful partner as well as the relationship, and support is often needed to heal emotionally and to decide whether or not the relationship should continue after...

You need to realize the person you loved and thought he was doesn't exist and never did. It was a projection of what he wanted you to see. The person you see before you is the real him.
Is that who you want to be with? It would be different if he committed to change and took steps to make that projected version of himself into reality. At least you could put the past behind and love the person he was becoming? This unfortunately is not the case. Stay strong.