The fact that you see there is a problem is a good thing. Now there is a couple thing I think that you can do.

One is to sit him down when he is not

mad. And tell him that when he gets mad you get scared.

do not say it mad or upset to him. Than ask him if he is will to go to anger managerment.
The other choice you have is to leave him. I know that it sounds hard but if you are scared of him than maybe that is need if he will not go to angry management