And it is my fault because..?

Sunday, I decided to take my mother and my oldest brother to Walmart. I knew that it was a bad idea for my brother to come because he does not like me and has always been jealous of me. But I let him go anyway. To make a long story short, we were all having a conversation and my brother was offended about something my mother and I said but because he does not like me, he put more of an emphasis on me. He started yelling and calling me b***ches, mothaf****, etc. and also called my mother and I jack***** and how I am not sh** and my son (who was sitting next to him) is not going to turn out to be sh** like me. He started talking about stuff my mother has said about me and my son behind our backs and of course as usual she did not deny it. But of course I already knew it was true because she has attempted to talk about me to my friends. During the argument, my mother was speaking for him and said that he is also talking about a previously situation that I did not apologize for (which I was not wrong in but my mother always takes his side) and I told her he is a grown man who can speak for himself and is speaking for himself. So instead of taking his abuse I dropped him off at the bus stop. My mother decides to get out with him because she was mad at me for dropping him off at a bus stop she did not want him dropped off. Then this morning, my mother leaves a message starting with "This is the lowest thing you have ever done..." and before the message could completely play, I deleted. So my question is, how is this my fault? For whatever reason I have always been the blame for most things every since I was a child.