Found nudes of my ex boyfriend's ex girlfriend - what should I do?

I (female) and my ex boyfriend (male) broke up a few months ago. Since then, we've decided to be friends with benefits and our arrangement has been working out very well, neither of us want to get back into a relationship and we like where things are. We dated for a little over a year. A little under a year before we got into a relationship, he broke up with his girlfriend of about a year/2 years.

I recently snooped through his room (I know this was incredibly wrong of me and I'm very sorry) and found a nude polaroid of his ex girlfriend. I'm assuming that he had this while we were dating. Also important to the story, when the conversation of nudes we had sent to exes came up while we were dating, I told him that I had sent my ex a couple nude polaroids of me, which he always responded that while he had sent and received nude pics through text, he had never sent or received a new polaroid.

So I now know that he lied about that, and that he kept a nude polaroid of his ex while we were dating. I doubt he really looked at the photo, but I'm not really sure how to feel.

I guess my question is 1) Is this objectively wrong on his part, is what he did really bad? I feel like I don't know how to think since we're broken up. And 2) should I confront him about it?

Really just don't know what to think and looking for any advice/insight on my situation. Thanks very much.