I was about to kill a person

Last week I was about to kill a woman because she insulted my mom. My father is a gamebler, he owned that woman money, now my father run away to other province and she come to my house and want me and my mom to pay for it. I said I will but not now, I don't have money right now. First she insult me, I feel normal with it. But then she start arguing with my mom (my mom has high blood presure disease and she had 2 stoke in the past). The moment that woman start insulting my mom I began to angry and push her out of my house. Then I go inside the house pull out a machete (my thought at that moment was to kill her), luckily my aunt heard the arguing and run to my house, she then stop me from kill that woman and take my machete. I think about this a lot, because I'm always a shy guy, I have never wanted to hurt anybody or any animal. Why did I do that??? I said to my family I just want to scare that woman but deep down I knew if my aunt didn't stop me I will kill that woman for real, and that make me scare, I scare of my thoughts....Please give me some advices. Sorry for my sucks English.