Chances are if the police are on the scene because of a call for domestic violence, someone is absolutely going to jail. California law requires that if a police officer sees a sign of physical violence and there is a relationship, that they are going to take someone to jail. This isn't like it used to be 20 years ago where they would just ask somebody to leave, or if someone didn't want a prosecution, the police could go about their business. That is no longer an option for law enforcement. Whether the person desires prosecution or not, if there are signs of domestic violence, they're going to jail.
It is a very serious misdemeanor. You absolutely will need a lawyer to try to navigate those waters. There are implications of violence that are associated with this crime. They can affect your rights to a firearm. There could be a restraining order placed against you. You could be required to leave your home and possibly not even see your kids.