@ghostt He talked about this earlier in an inner-monologue, when his step-mother came in person to threaten him. He considered simply killing her, but it wouldn't actually solve anything, and it would also effectively ruin his life and the lives of everyone connected to him, because then he would be the villain and no explanation he could provide would be sufficient. That's why he's going to such efforts to expose her and ruin her. That IS his revenge. He's cornering her and is preparing to air her dirty laundry to the kingdom. The entire reason he met with his father, which JUST happened, is because he wanted to hear with his own ears what explanation his father would come up with for why he allowed his own wife to be murdered in front of him, his only son be put into a coma, and then marry the woman who did it. He wanted a good explanation, and he didn't get one, that's why he wrote his father off and walked away, he's no longer concerned about the damage exposing the truth could cause to his father, because he now believes his father deserves whatever happens. He said as much, THIS CHAPTER, that whether they exiled him or not, he was going to leave the capital anyway because there is no further value in staying. The only reason he was staying was to get answers; he now has those answers, and is very unimpressed. He said, and now his step-mother said in this chapter for the second time, that leaking all the information he just stole to the right people would probably cause a revolution. He wanted to know if his father deserved what might be about to happen to him, or if he needed to change his plans.
This has all been talked about and discussed. Have you been paying attention?