Would you call this cheating?

Guy I've been with on and off for a few years. We ended things due to some of my depression which was only made worse when he started seeing a new girl a week after. Well we started talking again a few months later which turns to us dating again. I told him I wasn't comfortable with him talking to her due to lies he told me about talking/not talking to her. Today I was at his house and took his phone to check our sprint bill. Something in me said look at his pictures. Well there in his screenshots are pictures of her in bikini. I put his phone by him and left. Maybe it's just me but this feels like cheating. Anyone have any thoughts. I've ended things and I'm just incredibly hurt.