Sivan's hysterical episode ended with him fainting because of the exhaustion. He exhausted all of his energy and almost destroyed the entire estate if not for Butler Si constraining his attacks.
After he was out, Butler Si carried him back to the clan and let him rest for a while, and when he woke up, he is a lot calmer.
"I am sorry for troubling you, Butler Si. I was just angry at my incompetence."
"Never mind young master. I can understand your pain. But if the young master doesn't mind, I have a suggestion."
"Come on. Butler Si, you don't have to ask me permission for that. You have the right."
"Thank you, young master. I think that you are not angry at your incompetence, you are just angry at someone's competence."
"What do you mean?"