my brother hates me.😢

last night I walked downstairs to our basement to get more pop (we were having a Christmas party I was walking down I hear loud like moaning). then went when I got down to the basement (we have like in the other room in the in the basement) . I see my brother having sex with with his. boss who's also my dad's best friend. we live in a small town so everyone knows each other and everyone's best friends. he begged me not to tell my dad but his boss is literally 50 years old and my brother is not even 17. I don't know what was going on, what I saw my brother being forced and he didn't look like he was enjoying it you look like you was being forced into something like he was being blackmailed.lat I don't know.