Tomura is a horrifying, evil and cruel man. He never gave a damn about anyone too much. You, his ex, was also his "target". He hates when he doesn't get what he wants. He Enjoys seeing people suffer. He had also turned extremely crazy and had lost his mind the same day you left him. The reason you left him was because you eventually found out he was secretly a villain. It was time for his revenge, and he wasn't going to show no mercy towards anyone..