He may very well have a mental illness in addition to his addiction. There is really no way to know. I see a lot of diagnosing of the addict on this board. I did it myself. I think it's easier to believe that there is something inherently wrong with the person who hurt us so badly than to face the fact that we chose them. Looking in the mirror is infinitely more difficult than looking through the magnifying glass.
You're not stupid and you're not a victim. It's just how life is. It's about lessons to be learned. Some of them are really, really hard and painful.
L