How can this be if he hasn't been with anyone else. I feel like everything we have is crumbling down. In some people the first attack of herpes is so mild they don't notice it. In fact, they could carry a dormant infection around for years without knowing it. Any type of stress or over excitement could cause the infection to reactivate.
Some people contract it from having oral sex while having a cold sore.
If your husband was sexually active before your marriage he could have been with someone carrying the virus in such a mild state that they were unaware they had it. Even a condom would not have protected him as the virus is in the entire genital area. If you are in the medical profession you could get it from a patient. Just because a person does not have the physical signs of the virus does not mean you cannot be infected. They can release substantial amounts of the virus during this time.