Kat, if you can put your information down in an unemotional way, keeping just to the factual points it might help.
If you start a document of facts, putting each point down just as you think about it, you can keep adding to it until you feel you have enough points assembled. Maybe you can then put them into a logical manner in a letter to your mother, telling her how much you love and respect her, but... then mail it to her.
I don't know your circumstances, but if you could manage to be away for a few days it could give her time to digest it. This might diffuse the situation.
esther