Oh god I hate this crap. Someone is constantly passive-aggressive, victim silently suffers under it until they finally stand up for themselves and give them the what-for, only to realise they didn't know the truth/misinterpreted their actions/etc and is a horrible person for actually refusing to take their crap.
So remember girls, don't ever actually confront someone and the way they're treating you, you probably have it all wrong and break their poor little heart! Be a good girl and suffer under their good intentions!
Seriously, no mother could be THAT damn clueless. I'd say Sheila was right all along.