Does Kakashi regret teaching sasuke chidori?

only a little. now that Tobi told him the truth (Tobi=madara uchiha)

ofc he does, he was his only brother, and when he found out the truth, that itachi never stoped love sasuke, i think he regret it badly

Well, he cried after hearing the truth about Itachi, and he said that he cared more about itachi than the village, and he wanted to kill danzou and so on, so I guess so.