Chica,
the Stately Homes thread in relationships has a lot of stuff on it from ladies with narc mothers, and a lot of discussions, it may help to read that and find you are not alone.
It is a massive shock, and you will also realise that your mum is in fact a terrible mother as she is NPD so unable to relate to anyone but herself. However, as a narc, she has contructed an image of herself to the world that she is wonderful, and she collects people round her who feed into this construct.
My gran was the most horrible NPD bitch in the world and made my dad's life hell and also my aunt's. As far as the rest of the world is concerned she was lovely and so generous, and so kind...she was bully and a liar.
Anyway, try the stately home thread and try to calm down a bit.