My boyfriend called me a bitch cause I message a girl he wanted to fuck in the past

So I’ve been with my boyfriend 3yrs. I found naked pics of a girl he used to tell me he wished he fucked. They used to work together. He had these pics saved on his email. He emailed them to himself back in 2016 and 2017. Me and him started dating in 2018. I found these pics in 2020. All theses years he had them. He also followed her on every social media account he had. Mind you all these accounts I didn’t know about. He had secret accounts. That he followed her on. Anyway he told me today that he deletes text messages. So I messaged this girl to ask if she talks to him or if they ever had sex. I also told her that I deleted her naked pics. She said she can’t believe he still had them and said she was embarrassed. I told her that my boyfriend is obsessed with her. She said she never had sex with him. And that she was barely 18 when she sent those pics. My boyfriend at the time was 39. I told my boyfriend that I messaged her and told him that I told her I deleted the naked pics and said that I told her that he’s obsessed with her. He said “you fucking bitch how fucking dare you talk shit to her about me”. He said I crossed a line. Mind you he’s cheated on for 3yrs with cam girls. Did I cross a line? Why is he so scared of her knowing the truth