What should I do? Is it wrong that I feel like he has betrayed me?

My husband and i have known each other for the last 4 years. Since we met, we ve gone through a lot of problems like his family not being okay about our relationship, losing jobs, financial trouble etc etc. We ve also had our fair share of fights and arguments. Recently I found out that he has been paying for a dating-website membership. I actually stumbled across it last month but he said that his credit card had probably been misused. He also then called the bank and informed them that it was an unauthorised transaction and asked for a card replacement. But I found a couple of payments to the same website on another credit card statement (from a different bank than the older one). He then confessed to having signed up on this flirt-site and said that his intentions were harmless. He also said that he has been chatting with a woman about 'normal' and 'general' stuff. What hurt me the most was that he made it sound like it was my fault. He justified this act by saying that we fought a lot. He also doesnt think that this classifies as cheating or being dishonest. He did say sorry a couple of times, only to stress a minute later that now everything is okay because we arent fighting anymore. I never thought that this would ever happen to me. I hae loved him so much all these years and left my parents and even my education to be with him. I dont want to leave him, but I just cant forget this. Please help me!!