flower,
I'm sorry to hear your mother is in the shape she is in because of her belief the new system was near. Help her now to get whatever further education for blind she can get.
As far as letting her know what you are learning, I agree with everyone else. Take it slow. S. Hassan suggests slow, little bits of info to help people look at their religion.
Also, what are you going to offer her in return?? If you can't replace the hope you will be taking away with another hope, it might ruin her faith and I know that is not what you want to do to her.
This is a lot of information you are learning and "digesting" for yourself. For the time being until you are ready for the consequences, you might just want to be cheerful and live a life that would help her see that you are ok with God.
Just my 2 cents. j2bf