How can you bear to be near such a man?
I hope you do the decent thing and tell this woman he's keeping images of her. I'd tell the ex too if you're all still in touch. Your husband must have been perving on her when they were together. He's no friend.
& then leave him.
He's just a man - he's not God. Women get by in life without unsuitable men by their side, if you love him yes it can take time to get over, but you won't die for lack of him.
I'm not sure if you have a DD but if you do - when she grows up how do you think you'd feel/what advice would you give if she came to you and told you her man was behaving like this?
Men like your husband are harmful to women and it's often the woman they live with that spots the signs of what may be to come.
He has odd impulses, zero respect for women, and the day will come when he acts out whatever further warped fantasies he may have.
He could be out several times weekly stalking women for all you know. I bet he's not out there having a love affair that's for sure..he doesn't like women and whatever he's doing with one will be something sordid.
Stop letting him getaway with it under your nose, if you can't stand up to this creep then get someone alongside you who can.
This is an awful story and situation. I wish I hadn't read post and thread.
Get out for your own sake OP and if you can tip off another woman that she's the subject of an oddbod's obsession, then that would be a good thing for you to do.