My mom accidently leaft her christmas cactus out overnight and it froze , so she proceded to cut off all of the branches because they were all frozen and dead looking. It wouldn't be a big deal, but it was her mother's plant, and I would like to have my grandmother's plant stay alive for a while yet, since it has a sentamental value. Is there any hope of saving it? What can I do to make sure that there is the highest probability it will survive and grow again? Please Help!