Am I overreacting?

My phone was dead so I asked my boyfriend of 4 years if I could use his. I was looking at my books I needed for school online so I took a screen shot of all of them. I tried to select them all to send them to myself but accidentally deleted them. So I went to his deleted photos to recover them and I found probably 10 pictures of other girls boobs. The pictures looked like the girls took them themselves, so it wasn’t like a screenshot from porn of something. I confronted him about it and he said his friend sent them to him and he saved them to delete them because he didn’t want them on his phone. Of course I questioned this a million times but he wouldn’t budge on the actual story. It has caused me lots of self doubt and anxiety. What the heck do I do!!!