One of the reasons I sought out alternative religion was the hypocrisy and outright cruelty I encountered in conventional religion. I compare conventional religion to any paramilitary organization: You've got a chain of command and you are expected to follow certain rules.
The inherent problem with conventional religion is outside accountability; IMO it creates moral/ethical "wiggle room." In other words, you can do something rotten and get outside absolution of your behavior and you have a clear conscience. Wiggle room. The Bishop can treat your mom like shit and ask for forgiveness from an outside source, receive that forgiveness, forget what happened, and go about his life free of guilt.
Additionally, conventional religion provides for no explanation for what happened to your mother; it's an ineffable spiritual "mystery." In my spirituality you can either 1) be comforted by the fact that what has happened to her is either balancing a karma debt or will be balanced karmically in the future and/or 2) it's a lesson, and while not a pretty one or a pleasant one, anything that makes anyone feel THIS powerfully is an important lesson, a trial to be confronted, resolved and moved beyond, and that experience will not only shape who you and she will become someday, but that information can also be used, intellectually, in the future.
Your righteous indignation is perfectly understandable, but I would urge you to try to let the anger go. And then look at the situation from the point of view of the diocese (Wiccan playing devil's advocate here, how’s that for irony?). It's an "old boys network" don't tell me otherwise, and your mom is a woman having a "nervous breakdown." Men, particularly the older generation, have NO compassion for a woman with emotional problems, they don't give a shit WHAT the problem is or what generated it, she’s just the “weaker sex.” And no matter what, the church is a corporation. What they see is an "employee" who cannot fulfill her duties and could potentially be a strain on the resources, and may even impact parishioners, perhaps cause a loss of revenue.
I'm not saying any of this IS the case, all I'm saying is ... organized religion is a corporation

Its purpose is to make money and to be self sustaining. To deny that is to be naive. This is one of the big reasons why organized religion worships in buildings and pagans worship in the fields. You start building shit, acquiring stuff, the spirit of the thing disintegrates. You have to start worrying about WHAT you’ve gotta do to KEEP your stuff and very often, the things you need to do to take care of your STUFF are at diametric opposition to what you need to do to take care of your spirit.