Even if he stayed in konoha he would've mastetd sharingan since kakashi was there , and he would've ended up fighting against itachi anyway since that was itachi original plan
As for killing itachi, you don't just kill your ****ing brother like that, he could've just asked for what happened to him **** If itachi was my brother I wouldn't ****ing kill him without hesitation like that and any why would he listen to a masked man that he just mwt after he killed his brother and suddenly want to destroy the whole village, sasuke did alot stupid shit bruh
I'm pretty sure Sasuke felt that way about -----------
his whole family.Going to Orochimaru lead him to mastering the CM which before restricted him.He also left to get rid of all his bonds that he had that je felt were holding him back.
While Tobi was telling him about Itachi,Sasuke literally said multiple times that Gobi was lying,and he figured Tobi was right from thinking over everything that he said and piecing it together - it did make sense,and he didn't completely believe everything Tobi said,hence Sasuke saying this after asking Danzo about Itachi.
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"So it was true".
Also take a look at the pages before then - he ask about Itachi,sees that what Danzo said about Itachi matches up to what Tobi said and then Sasuke says,"So it was true."