In the US, what he's doing might fall under Invasion of Privacy. There are four categories under modern tort law. The first is "intrusion of solitude", which is the physical or electronic intrusion into one's private quarters. The second is "public disclosure of private facts", the dissemination of truthful private information which a reasonable person would find objectionable. Thirdly, there's "false light", or the publication of facts which place a person in a false light, even though the facts themselves may not be defamatory. Lastly is "appropriation" the unauthorized use of a person's name or likeness to obtain some benefits.
Unfortunately, if you gave him the pictures and they're on his computer, it's not an "electronic intrusion"; he technically owns them and has the right to distribute them as he wishes.
You may be able to make a case for "public disclosure of private facts" and "false light", so I wouldn't give up hope just yet. Every email can be traced back to an IP address, and every image is embedded with a digital signature of its origin, so he cannot claim that the files were not sent from his computer. I would urge you to talk to a lawyer (they'll usually evaluate your case for free. This site has electronic forms you can submit, if you're worried about tracking down a decent one). It really sounds like it's the best chance you have to get this situation sorted out with the least damage.
Good luck, I hope this helps.