Contact your local Police domestic violence / family support unit ( it may have another name, but it`ll be along those lines ).
It`s likely to be based in a bigger police station, not the smaller satellite ones.
Ask to make an appointment to see an officer from there. It will be at a time and a place that you feel safe / comfortable with, if you don`t want to go to a police station. They don`t wear uniforms, so if you met in somewhere like a cafe, no one would know who you were with.
They`ll give you advice and get the ball rolling, about how to get either and injunction or a restraining order against him. Plus they work closely with shelters and womens groups, who help and support the families of domestic violence, such as yours.
Everything they do, is absolutely confidential, so there`s no way he`d find out what you`re doing.
The police get slagged off for many things, but these units, that support women / families such as yours, are staffed by people, who are totally dedicated to their jobs and go above and beyond.
This first step is the most important step and the one that ultimately change your families life for the better.