Hi Gingersnap,
Just be there for her - allow her to express her feelings - and then help her focus on what she can do to manage her illness. Hopefully the dx will not be MS but if it is there are several DMD's that she can take. Her Neuro will explain all this to her.
Tell her about this web site - it's awesome and there are some wonderful people here.
I'll be thinking of you both - take care.