I know you are knew here and some of the name calling or disapproval of the cheating spouse may offend you. But you have to understand, most of the people here are trying to save their marriage. Unlike you and your openess with your H, many of us were lied to, hence the 'betrayal' aspect.
I agree it is not wrong to THINK about divorce or separating, but is is WRONG to have an affair with someone else while you are married. It is something that the cheating spouse should feel guilty about. It is immoral after all. However, I truly believe that BOTH of the partners contribute to the factors that lead to affairs. It is not like they woke up and said hey I want to have an affair and leave my spouse. It must take a long time to come to that point. So if one partner is truly unhappy, should they not communicate their needs and feelings to the other? To see if the issues can be resolved BEFORE cheating? I know that in reality this is rarely the case. Unfortunately, an affair is usually the wake up call, and it usually happens when the unhappy spouse has already given up on the marriage. very sad.....