Sounds like they're going through some shit and using toxic online interactions in an effort to try to ameliorate their internal struggles. It reminds me of a wounded animal lashing out.

Doesn't justify them, but it does give more context so people can respond accordingly.

TBH I felt this is something they made up once it got more attention. If they had felt remorse, they might have come back to apologise or correct their mistake, sometime in the past two weeks I guess.

Who knows maybe they are really ill. Maybe they just made everything up.