"Couldn't care less" actually used correctly...if I were an English language teacher, I'd be weeping tears of joy.
(For non-English speakers, the phrase is often rendered incorrectly as "could care less", which means the person still cares, even if only just a little bit.)
Younger brother is a dick, don't even feel bad for him being bullied/isolated before timelap, and i bet him being a piece of shit was a reason for those.