Domestic violence

A friend called me and told me that she is having issues with her husband. According to her he has all of a sudden developed a quick and bad temper. He flares up at every flimsy opportunity. Some days back he came home late and met dirty dishes in the kitchen and called on her before she could explain he gave her a blinding slap. She was dumb founded and was in tears. He pleaded and begged for forgiveness. Her female friends are saying it's nothing. I told her to be careful. What do you think she should do?