You aren't a horrible person because when you think about it, his plans didn't work so since his plans didn't work it was just an attempt and when you really think about it he didn't want to kill anyone he just wanted to turn people into puppets and sell them, but for Riddle as much as I love him in the manga he killed Cater's clone who was protecting Deuce from the attack Riddle threw at him, and before he overblotted I mean he yes he was in the process of overblotting but he did try to hurt Ace. Also Azul, I'm pretty sure sucking people's magic from them is kind of an assault in the magic law, Leona used his unique magic on Ruggie's arm, Jamil enslaved the whole dorm and tried enslaving Azul, Idia and Ortho were trying to destroy the whole world to "fix" it they also kidnapped people well they didn't do it themselves so they would be considered a accessory. Also don't let me forget, Ruggie started a stampede and used his unique magic to hurt people, his dorm mates helped in doing so, the tweels are probably apart of the mafia. Deuce was an delinquent in the past, Epel probably hit people to show them not to underestimate him Lilia was in a war that should speak for it self, Rook stalks people specifically beastmen, Ortho was about to nuke the school if no one helped save Idia. - - - - - spoilers - - - - - Malleus put everyone in the school and land including my Neige and Chenya under a sleep curse. So to be completely honest, if you were a bad person for liking Ferro then everyone else who likes those characters would be considered a bad person.