am I wrong for being annoyed.

I just feel like I have to rant because I’m starting to go crazy, I’m 22 my boyfriend is 23 we have adopted his little brother his 11, he plays fortnite on the PlayStation none stop but we have given him times he can go on because he gets to loud when his talking to his friends and just shout so his allowed on it for an hour after his come home from school and does his homework, so this is why I am annoyed when my boyfriend tells him to be quite he says ok and stops, well I was just upstairs and he started shouting so I said ‘wow calm down your being too loud’ and he’s response to me was ‘shut up’ now I’m even more annoyed because I’ve none him since he was 6 and me and my boyfriend have both adopted him so when I tell him to do something I expect him to do it, I told my boyfriend what he had said and he said he will talk to him but I don’t think that enough his starting not to listen and it’s getting to the point where I’m starting to loose my Shit.

for everyone talking about the legal adoption we are legally responsible for him as his mother passed when he was younger and in her will she wanted us to legally have him so we went through all the stages of having him and me and his brother are the only family he has and we are in the UK so wasn’t hard for his brother to take him, signed some paper when his mum was sick and just like that we are legally his guardians.