I think it is very tough to go back to work as soon as you did, that in itself would be enough to make a person cranky, but you're also coming off the anesthesia and other meds you were likely taking before...top than off with discompassionate co-workers and you've got quite a mixed bag of negative forces working against you.
I'm afraid I don't have any good adice as to what you would say to your co-workers, seems if they have it in themselves to act as they have already... If you can though, might be good to give yourself a little more time for rest and recuup?
Love,
Janet