In Japanese culture, the words 'go die' are quite serious, almost equivalent to 'idiot'. If said between family or friends, it almost equates to breaking off relations.
So Minamoto Tamako regretted it as soon as she said it.
She just wanted to express the meaning of "Mr. Fushimi not actively seeking treatment means just waiting for death," like picking the worst option out of two, and not actually cursing Mr. Fushimi to die quickly.
After returning to her room, Minamoto Tamako lay face down on her bed, covered herself with a blanket, her mind in turmoil, not knowing what to do.
Fushimi Roku, on the other hand, didn't think much of it. In his past life, he would joke with ordinary friends by saying 'go die', and in his context, the severity of saying 'go die' was about the same as calling someone an 'idiot'.
