1
general::
Phrase(s): nurse a grudge (against someone)
Fig. to keep resenting and disliking someone over a period of time. (Usually implies that it has been an unreasonably long time.) • Sally is still nursing a grudge against Mary. • How long can anyone nurse a grudge?
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Bear resentment for a long time, as in We don't know why Karl looks so angry; I think he's nursing a grudge against the family. This expression uses nurse in the sense of "foster a feeling," a usage dating from the mid-1700s.
American Heritage Idioms