My sister just went crazy and I'm feeling terrible ?

You didn't do anything wrong. No one enjoys listening to those sorts of heated political debates, it's irritating, and the debates usually just go in a frenzied circle and denigrate to personal insults after awhile. Your sister clearly has some emotional problems. Your mother should talk to her about this after she calms down, try to analyze what has got her so upset. Maybe she needs a counselor to vent to; it's possible her inner emotions are just building up and exploding in outlets that aren't at the core of the real issue. But as she seems to be lashing out at you at the moment, I would just stay away. Give her space til she calms down, and let your mother handle this. If she gets violent again, depending on how bad it gets, your mother might need to call the police to keep the situation from getting out of hand. But unless your mother specifically asks you to do something, I would have no involvement. You'd probably only make it worse. Just go to another room, and wait it out.