Is this cheating?

Last nite I went through my boyfriend's (of one year) phone and found some bra and panties pictures of a girl. There were 7 and they were dated at all different times within a 3 month period. When I confronted him, he confessed and said he knew her years ago but she now lives in California. He said they would Skype (which he and I have never done) for a few hours at a time. He said he was lonely because I wasn't giving him the attention I used to give him and he just wanted someone to talk to. He said all they did was talk about hobbies, and that he never asked for pictures from her, but that she just sent them. He also said he never sent her any of him. I know they never met in person because she lives so far away, but I still consider this cheating. I'm curious what u all think.