The decision to call the police when domestic violence rears its ugly head is not an easy one to make. Many women feel that they do not want to involve the police in a purely domestic argument. Others consider the impact on the children that a visit from a squad car and several policemen will have on the children's emotional health. The decision to call the police or not must be decided on a case-by-case basis. Certainly where there is an assault of a spouse or children in your presence, your safety and the children must be protected, so a call to 911 would certainly be indicated.
However, where there is a single episode of mild foul language spoken in the heat of a verbal argument, the answer might be to defuse the situation yourself by walking away, rather than placing a call for help. Nonetheless, you should never be timid about calling for help when the situation demands such intervention.