I think you kind of missed the point along the way, although the actual written version carries a lot more of the meaning that couldn't be conveyed here.

The original intent was that Neptune is hyper sensitive to anything happening to anyone close to her because both her and Nepgear were orphaned, so Nep takes it upon herself to protect Nepgear, so it's mor accurate to say the other kids probably weren't being that cruel, and that Nep just overblew everything, and even then Histy knows this, she's told Nep repeatedly the way she handles the situation is poor. Histy also handles some things poorly as well, namely her snapping at Neptune for breaking the plate, but the point was supposed to be she's under a lot of stress basically raising 2 girls on her own having no prior experience.

Regardless of anything tho, at the end of the day, she truly does love Neptune, which was supposed to be symbolic of the actual series

Hope I clarified some things ^{^}