You did say it in the OP. Apparently, you knew it all along. You showed lack of good judgment and caution in having the nude pictures taken by someone who is unpredictable in his behavior. Your OP talks about his being one way this second and the opposite way the next. Whether it is just the way he is or caused by the schizoaffective, you knew that this was the way he was. So... you were in the know. In other words, what happened, happened not like a natural disaster, all of a sudden, but could have been predicted. Especially with the schizophrenia part - what if, if you give him a chance now, he will later claim that some voices in his head have ordered him to send the pictures of you to your teachers - the pictures which he, inadvertently of course, forgot to delete from his backup?

So I think that you have not solved the problem with the deletion of the files and that a RO (restraining order) + police involvement + possibly hiring a lawyer are still the best options in the long term. You repeat that you just cannot get through to him even though you have tried. So, OK, accept that you have tried enough and have found yourself unable to get through to him and, consequently, will need to pass down the task of getting through to him to the legal system.