To deal with someone who abuses women, you have to stay calm. If you are not calm, no one else will be, and things will escalate, and it will be very bad. You need to keep yourself away from the situation, and call the cops. Let them handle their job. If you decide to get involved you need to stay calm, don't yell or swing at the abuser or anyone else, try to diffuse the situation without making it worse. If all fails, then call the cops and let them take over.
