so was the nutmeg thing on purpose?

It was more aimed at Blanche not the MC. But it probably would have killed Blanche.

it was added in later in the hallway by the aunt (?) pretty sure the mirror boy saw everything so we'll probably know in the next chapter~

and yeah the aunt (?) did it on purpose, to make it look natural instead of plain poison

Ya it was definitely on purpose but she didn't expect the effects to be that strong and just wanted blanche to have a stomach ache, but if blanche was the one to eat the food she probably would have died.