"Violence is never the answer" is something you tell children because they do not yet have the capacity to understand the nuances of how and why violence can be a useful tool. Violence is one of the greatest tools of change that humanity has. It has done more to shape this world - for better or worse - than anything else in history. Violence can destroy and degrade, but it can also be salvation and lead people out of suffering. The problem is not violence, but rather how and why it is wielded. When used against those who oppress others, violence is a righteous act that can provide freedom and justice.
Violence should not be the first option, but it should not be off limits either. If talking it out fails to stop the violence you face, then violence in return is a justifiable response.