Sexual addiction can be used as a lame excuse, but I do believe it is a very real issue. Sexual addiction is just another coping mechanism, we get a high from sex and from arousal just like all other drugs. This high makes us feel good, feel wanted and allows us to let go for a moment or two. Your husband is probably trying to fill a void within himself or using the arousal from the interactions to feel wanted and needed.

I agree with Hamster_Bamster... it seems like your husband wanted you every night and probably was denied often, just assuming here, and eventually gave up. His insecurities and emptiness only grew with this possible rejection and his "addiction" and actions became worse. Your possible rejection is not exactly the issue for his addiction seeing as to how you said this has been happening for awhile and you only been married a year?!?

I suggest you two seek help: Couples Counseling, Sex Addiction Therapy and you both probably need individual therapy. A possible separation is another suggestion. You have to take care of yourself and your feelings. Something like this can really destroy your psyche and your self-worth and will destroy trust. Its going to be a slow process but if you both want it to work than you will persevere.

Best of luck!