My Boyfriend is saving pictures of other girls, what do I do?

Am I overreacting? I found my boyfriend has been saving pictures of girls to his phone, there were hundreds and he's been saving them daily. From them being completely naked to not at all. They all have similar features, complete opposite to me. I felt so hurt and upset to see this. I don't know why he would need to save all these pictures. we've been together almost a year. Please help me understand, am I in the wrong? It's not a body image thing, I just feel so disrespected. I also can't seem to get past this, it's playing on my mind a lot. But now I feel guilty for finding the pictures. It was completely unintentional, I had his phone to take photos while he was in the bathroom and he had left the camera roll open.

I'm overreacting and need to get over it
I have every right to be upset and this isn't normal boyfriend behaviour
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I forgot to add that I've talked to him about it, he told me that it's not like he's cheating because he doesn't actually know them. He doesn't know why he does it and it's probably a body image thing for me.
My Boyfriend is saving pictures of other girls, what do I do?
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