Why is he unable to forgive my one mistake?

My husband and I have been married for just over 3 years. Within that time he has admitted to cheating on me 5 times! Each time he apologized and promised to never do it again. Well, he recently took a new job and has to travel a lot. I initially expressed my concerns b/c I did not want him to cheat while out of town. However, about 6 months ago, while he was away for 2 weeks, I met a man and it led to an affair. My husband just found out about it and is now very upset with me. He even talks about divorce. How do I get him to understand that it was a mistake? Is this marriage worth saving or is he a hypocrit not worthy of my love?