Hi Birken,
I'm so sorry to hear of your abusive situation and that you had to do bookings that were not of your own free will. That is so sad and I am so sorry you had to go through that.
As others have suggested you could try and ask him if he could please now delete the pictures? You say he seemed sometimes to be kind, so he may accept your request and just comply possibly. If you feel OK about being this open, you could also tell him that you were coerced/ in an abusive situation at that time and hope that this would cause him enough remorse/guilt to do as you ask. However if you do this you would have to be prepared for him to say no, which of course would feel very traumatic for you. Also that he could say yes to deleting the pics ... but you would never really know if he had x
Ultimately, and I know this will be controversial and difficult, but I think you might have to work on acceptance of the situation, self compassion, and the completely compelling and understandable reasons why you allowed him to take pictures at that time. Because if he doesn't want to, forcing him through legal channels is likely to be a near impossible task.
Remember having those pictures in existence does not make you wrong or bad. It sounds like you have a new life now and are doing well. If the client won't delete the pictures might you consider counselling to move forward, and to try placing your focus on your new bright future rather than the past? Easier said than done I know x