I also think that NPD is almost impossible to diagnose, but it seems he is a whole lot more narcissistic than you are, and the abuse is narcissistic in the sense that he acts like he's entitled to abuse your trust and exploit you, and any backlash is viewed as inconvenient. He basically acts as though he is more deserving, which is narcissistic. He could get duped in the same way by someone even more narcissistic than himself. There just isn't enough balance for your marriage to be sustainable, and I think you're doing amazing to see it for what it is. Hope you can find your way out soon