What can you do to a person legal wise?

if they continue to put a camera in your face like really in your face during child visitation.. my gf has a child and is goin to court for custody but the childs dad is a dead beat and only wants to harm my gf he doesnt even care about the child. well now every time she drops the lil off to go with him he brings his wife and they harras her with a camera intil she starts to cry from being so angry...now me im in the army and im coming home next weekend and i have the mind to break every bone in his body considering im goin to the sandbox and i want her to be ok while im gone but is there anything legally she can do...