Went through my small brothers phone

My younger brother and I are really close. I consider him to be my best friend. He started watching anime recently. As someone who also watches anime. I know that there are lots of shows with fan service in it, I stay away from them because they make me uncomfortable and ruin the show. I guess for men it's different, but recently I saw him watching a particular show that's known for its fan service. I gave him the benefit of the doubt and thought maybe he'll skip those scenes.

The last few days I've been having a bad feeling. I decided to check his phone. And I'm disgusted. He's been visiting NSFW sites on reddit about those shows. Some of these subreddits are to do with anime r*pe scenes. I feel sick. As his sister. As a woman. I don't know what to do. He's a very intelligent child, he's also studying the quraan, he is a hafidh. Hes kind, generous, He's respectful to me and my parents. I regret going through his phone. It obviously changed how I see him.

I don't know what to do. I don't know who to talk to. I don't know if I should tell my parents. Please advise.