The fact that your presentations were not for re-sale is irrelevant. Unless the images are in the public domain, you may not copy or display them without the copyright owner's permission. You exposure depends, in part, on whether the pictures are registered. Please feel free to contact me ASAP so that we may explore your options and protect your legal rights. 973-921-0600.
Kindly note and remember that my response is merely a general comment on the law related to your question, and NOT legal advice or opinion. Also, your question and my response does NOT create an attorney-client relationship between us. You cannot rely upon what I have written, because I do not have all of the information that I need to advise you or render an opinion. Even simple facts you have not shared can completely change my answer. For me to give you legal advice or opinion, you would need to hire me to be your lawyer, and then we would need to discuss this in detail and go over the documents.