my step dad snapped last night, it is hard for me to talk about but i think it will be good for me to tell someone.

he has always been unpredictable but last night he lost it, i was not there but my mom told me he went insane, throwing things and swearing and he drew the line when my mom threatened to call the cops and he said it would be the last thing she did...... i want to know what i should do i am scared for my moms life????