Luckies4me, I know this must be very difficult for you right now, and you just cannot understand where she is coming from, everyone reacts differently, I did not experience this with my mother, so I don't know how to advice you, except to say HANG ON IN THERE, as others have said she may change her mind.

Now stop all this talk about dying, Cancer does not mean death, and besides nothing has been diagnosed yet, so try and think postively.

It is an odd reaction, to me, but until we have walked in those shoes, none of us know how we will react.
From what other's say it is normal.

It is hard to be supportive if she is withdrawing from you, but do the best you can, remember she is in a terrible state right now, very scared, and she NEEDS YOU., whether she thinks it or not, you may just have to be the forceful one here, if she does not change her mind, and say Mom I am coming to see you and help you out and that is that.