He still has pictures of his ex

My boyfriend still has very nude pictures of some of his ex's and he wants to use them for black mail because they owe him money and they don't want him showing them to anyone so he's going to use those to his money back. He's showed me some of them and he tells me he wants me pose or wear something like they are wearing in the pictures. I'm not too comfortable with him having those, I said to him, "it kinda makes me feel like you are more interested in them more than me" and he said, "no, I'm more interested in you, it's just good to look back on the kinds of sluts I used to have so I know how I want you to be. It sounded pretty hot but...I don't know when we are both horny it's all just horny thoughts really. Should I tell him to delete the photos?