All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
There is no doubt that your husband has committed a great sin by saving such photos, and the sin becomes even graver if the women are naked as you mention.
Thus, your husband should repent and delete these photos. If you are able to delete the photos without your husband harming you, you should do this. However if you are unable to do this, then you should advise him and warn him against the punishment of Allaah if he does not repent. If he repents, you should thank Allaah for guiding your husband and that you were the reason for his guidance. It was narrated that the Prophet, sallallaahu ‘alayhi wa sallam, told us that guiding one person to the right path is better than possessing all the treasures of the world. [Al-Bukhari]
However, if he does not accept your advice, you would not be sinful, as you have advised him.