I live with my family, and my 18 year old brother is in college and lives in the dorms, but comes home every once in a while. He is home for spring break now. I don't know what his problem is, but he has this habit of getting pissy and starting **** with mom for stupid reasons. Last night she wanted us to get something to eat so she implied she wanted to eat too, but then only asked him to get something small for her, so he started accusing her of not actually being hungry and lying about it because she wants us to get something to eat. He started sitting around acting pissy and being an all around jerk. Eventually my mom started getting upset too and telling him he shouldn't be getting pissed off about such a thing. He started saying how he's pissed off because she always does this and how she doesn't listen to him and isn't being honest, bs like that, I'm pretty convinced that's not what it's about and he has some deep seeded issue and wants to create drama. Anyways, he wouldn't let it go and my mom ended up getting pissed off too. Today my mom sat in her room all day and didn't speak to anyone, even turned her phone off. Not sure if my brother apologized or what, but I heard him talking to her in the morning and they yelled at each other for a bit. My guess is that he tried to talk to her and she is refusing to let it go.

I have no idea what I'm supposed to do now. My brother behaved like a self-centered jerk and I am really pissed off at what he did, but today he was being nice with me and I just can't bring myself to be mean to someone who is not being mean to me, it just feels like it would be cruel. So I pretty much acted normal with him like nothing is wrong between us. I always do this. Am I doing the right thing? Should I not care about being cruel and just be mean to him when he's just asking me if I want to play video games? I don't know if I am capable of doing that.