If I were your boss my concern would be how easily you succumbed to blackmail, so don't mention that. Would you be willing to give her company passwords next ? I also wouldn't want to be part of your personal drama. If I got these pics as your employer, I'd delete them and tell you FYI, I got an email and deleted it and I don't care. Again as long as you don't mention you paid blackmail money since that could imply you did something illegal, like underage sex (I know you said that isn't it).

While the above may seem insensitive it was actually intended to put your mind at ease. I was in a similar situation ~10 years ago. I couldn't sleep, I thought my reputation was destroyed. I then reached out to the website where my fake revenge porn pic/profile was posted (it was a bad fake but still humiliating) and they took down the post. After I found my attacker's personal address and mailed a letter to his wife telling them I'd sue them for their house and assets if it continued. It all seems so petty and silly now but at the time I felt like my life was being destroyed. All because some SEO marketer stole my website, possibly source code, and App reviews and I wrote him a scathing review stating such. I was really just mad that he stole my App reviews since those belonged to my customers and were not mine to steal but I digress.