Oh, Alfred, how terrifying! I am so thankful your wife is better and at least was able to remember part of the cruise. I would assume the $61 was for port fees? I cannot tell you how they calculate anything since I don't work for any cruise line and am not a travel agent. I would assume something is stated in the passenger contract about this. I believe the incubation time for the norovirus is 3 days, but am not sure as I am not a doctor or nurse. It is possible your wife did come in contact with it on the ship, but also possible it was somewhere prior to boarding. They do a marvelous job in turning around a ship and making sure it is clean, much better than our hotels. The only prevention is continuous hand washing/sanitizing. I'm very glad you and your children were not affected by this virus.
I know this was NOT the vacation you wanted and am so sorry. I'm glad that RCI took good care of your wife and she is safe and well.
I do hope you don't give up on cruises, they really are marvelous vacations.