CM, condolences during your difficult time.
Here's some of what worked for me:
1) forget about it. Throw yourself into books, video games, tv, anything. Just try to enjoy yourself. Hire a prostitute.
2) this is out of your control. All the sadness, pain, and worry will /not/ help your mom. So do anything you can to put control into your life. Organize your sock drawer, eat all of one food on your plate before eating all of the next, exercise. Find some element of your life that you can control, and control it.
3) write. Create a world with characters going through what you're going through. Find out how your characters deal with it, then go and do likewise.
4) grieve. Go ahead. She isn't dead, but you're afraid she'll die. So go ahead and grieve like she already has. If she lives, you'll be grateful. If she dies, you'll deal with it better.
I hope these suggestions help you like they did me. Again, condolences.