It's also possible Carnival will offer you to change the cruise date (for a change fee) You will probably have to agree to use the changed cruise in the next year or something but its better than being out the money.
I won't harp on the insurance thing. Like you said.. you had every intention on going on the cruise so you didn't think you needed it.
I wish her a quick recovery!
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007