Tad, I know it's easier said than done, but you've gotta stay strong for her. Surround yourself with friends and family. Vent when you need to, it only makes it harder on you when you try to keep it bottled up, or try to hide emotions.
I went through a very similar situation with my Dad almost a year ago to the day, so I can relate. It's very difficult seeing them in so much pain and being limited as to what you're capable of.
Stay strong bud!