Need advice please!

My boyfriend is in a bunch of group chats with his friends and he was going through the pictures in one of them to show me a pair of shoes he wants and while we’re looking through the pictures I start seeing a bunch of pictures of girls tits and each picture was getting progressively more disturbing. I got pretty mad and asked him to delete the pictures from his phone because I don’t like the thought of him having that stuff in his phone. Then he tells me “so just because we’re together means you’re the only person I’m allowed to see naked?”. At that point I was disgusted. Him saying that just made me think, is that a lot to ask for in a relationship? Am I over thinking it? I know I can’t control what his friends send but is it too much to ask my boyfriend to delete pictures of other women off his phone?