Cheating?

I can’t tell if my boyfriend admitted to cheating or not in these messages. This convo was between him and his old friend. He claims he didn’t do anything but everyone’s saying he did. (Everyone meaning this girl and her two cousins he apparently fucked one of the cousins) He also signed up for some adult sexting site. He’s 16. I’m not ok with all this...am I wrong for not being ok with all this?