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...
The fact that your partner refuses to talk about it with you further emphasizes how weak of a coward he is. I would advise you to dump him, he's a waste of space and someone who is undeserving of a loving person such as you. The odds are also great he will cheat on you again.
It took my wife a couple months to get a better understanding of this. Her counselor also helped her gain some clarity to speed this up.