Am I Overreacting for Being Mad for my brother saying the N-Word?

I like to start by stating the obvious that my entire family is white. This all start with my brother and his computer, I also would like to mention that he is autistic and diabetic, He is a big fan of discord and Roblox. This is important because I noticed on his Roblox avatar that his skin color was way darker than it actually is.

He is always screaming on the computer and before you ask why my parents even allow this is a whole other thing (if anybody ask I will get into it). If it’s not obvious already he is an incel.

I was on call with my friend (who I like to say is Dominican and Black) and my brother was screaming the N-word, my friend started asking what that was and I had to lie saying that was a song playing because I was too embarrassed to say the truth. I hanged up on my friend and immediately went down stairs to yell at him about it and to tell how wrong he was for doing this and that I will make our parents take away his computer and then he punched me. It took 2 hours for our parents to come home and then they pulled me away and told me that they can’t do anything about it, that I should be mature enough to know how he would react.

I would like to end off by saying I’m 14, I have a job that doesn’t pay well, so I can’t move. I do have grandparents but they are even worse, and now I’m questioning if I’m overreacting about it.