I know EXACTLY how you feel. Once I had this fight with my younger brother I was actually trying to make him calm down, but when he gets angry he gets crazily violent and just decided to swing out and kick me for no reason and with no thought to it I just got him in the face and gave him a bruise on his eye. Since then I've never used violence on my siblings since I don't think the feeling of guilt has ever been so powerful and strong for me.