You can get an injunction, but will it make any difference? The guy in question doesn't sound like it would stop him. You could try though.
Meanwhile, keep records of everything that happens. If he verbally abuses your son, write down everything that was said and get any witnesses to do the same. If your son suffers any injury, no matter how small, or if criminal damage is done, take pictures and keep details. Then if you do go down the 'broken injunction / restraining order' route, as least you've got a record of exactly what happened when.