there isn't anything he can do. I personally would've hung up on him as soon as he raised his voice. I suggest taping your phone calls with him if he ever calls you back and threatens to harm you/family/possessions and get a restraining order and be done with it. Stupid people exist in this world, and sometimes you can avoid them, but other times it's just sheer luck and fate that stuff turns out like this. Either way I really would not be too worried unless the situation escalates from here.
"It's been my experience that straight-line acceleration is probably the first aspect of automotive performance that any intelligent driver gets bored with." - Peter Gregg