"Imagine having a mother and a father and aunts and uncles and you find out your brother killed them. That messes with your head."
But unlike Naruto Sasuke knew who was responsable for killing his clan which was Itachi. But he took out on innocent villagers being mean and nasty to everyone he met when they were treating him nice he was at the top of class his teachers praising him you could always tell also that Kakashi favorited him over Naruto and Sakura due to him always wanting to train Sasuke it got to the point where Jiraya and Tsunade had to step in. He betrayed the village and joined Orochimaru and the sound four's side, laughed when he heard Naruto and the K11 risked there lives for him, stabbed Naruto in the chest with his Chidori, tried to kill him in cold blood twice and was going to destroy konoha with Orochimaru using his body he knew that but didn't give a ****. This is all before he even found out the truth.
"and ofc he would go insane even after finding out the truth, knowing his clan was destroyed over the village is tough. Sasuke got all messed up because all of the events. He believed something but when he completed his goal(kill itachi) and found out that your brother was somewhat innocent it doesn't help you get better."
He also knew that everyone besides Danzo, Hiruzen and the other elders were innocent too but dosen't give a **** about them. He nearly and probadly would have killed Karin if Sakura didn't heal her someone who has done nothing but heal him and saved his life twice if it wasn't for her he wouldn't have even found out where Danzo was located in the kage summit not to mention he also betrayed Suigetsu and Juugo and left them for dead in the kage summit if it wasn't for them he would have died aganist Bee let alone aganist the Kages and Danzo. Evaded the cloud village and attacked and tried to capture Bee. Now declaring that he would destroy Konoha right in Itachi's face after all the sacrfices his done for him he basically said "**** you Itachi im doing what I want." this is why I cant feel sorry for him he takes everything out on people who have nothing to do with what happened to him.