Witnessed something terrible

So this is about my ex and his friends. He added me to one of his friend's group. This happened 3 years ago , that was his 1st year in iitk. Then comes the fresher's, they all were happy to meet their new mates and all. That night they were talking about all the people they met and everything then they started talking about all the girls. It still disgusts me till this date how they all were talking about them like how one girl was wearing backless dress I bet she's not Virgin, she was wearing such a short dress I bet she'll let me fuck her. This continues for hours, cheap comments and how they will do things with them. I immediately left the group, asked my ex to confront his friends he refused little did I know he was cheating on me with a girl 5 years older than him. I took screenshots , send to their seniors I don't know what happened after that.