I was in your exact same position in high school, though I didn't cope as well as most people.

If you have a good family and people that will listen, talk to them. The grieving process makes you feel a whole lot of things that are really confusing and its best to be able to tell someone who cares about you and won't judge what you're feeling. Remember that your family members are grieving also.

Remember that the death of a parent doesn't have to define who you are and her illness / death doesn't have to be the center point of your life. You're your own person who is having to go through something terrible, don't forget that.

Spend as much time with her as you can. Tell her everything you can, both good and bad. Make the most out of every second you can spend with her. Enjoy the holidays in the hospital (if it gets there) because they're better than nothing. Try to make as many memories as possible. Learn as much as you can about the person behind the Mom persona, she's her own person too.

The most important thing though, is hope. I hope your Mom makes it and I hope she sees you graduate. Don't give up.

Much love dude.