Hi Nelly, so sorry to hear your Mom's news. I can tell from your letter that you really love your Mom, which means she has probably been the best Mom in the world!! (besides mine, )
Just be as strong as you can be for her, she needs you to be. I understand her not telling you about it, my Mom did the same thing. We are waiting right now to find out about a 2nd Dr.'s diagnosis on Leukemia for her. So, I do know how you are feeling, its a kick in the gut, huh?
I am praying for you both, just love her with all of your heart, soul and breath, have some good long talks too!