When should you say something???

The other day my 5 yr old daughter was being a HUGE brat. She was being sy, disrespectful, and was refusing to obey her dad when he told her she couldnt go out back to play because she hadnt cleaned her room yet. Finally he grabbed her and ed her. We dont often in our house but it does happen sometimes. Usually I just give out on swat on the . My husband ed her 3 times and the swats were alot harder than I usually give. No she didnt have any marks or bruises but I thought he was to harsh with her. After he had ed her I told him that he ed her to hard and to much. He was furious and said that I undermined him in front of the kids. When I talked to my mom about it she said the same thing, that even though I thought the was a little to hard that I should have talked to him privatly and not said anything in front of my daughter unless he was abusing her. Opinions on this????