I don't know what to do.

Today is my brothers birthday. My mom and dad got in a fight usually they just have an argument, one of them apologizes, boom. Problem solved. But this one is different. My dad apologized and it seems like my mom doesn't forgive him. I can tell they are not going to get a divorce or anything, but this fight might last a couple of days, it might not. I don't know. They've gotten into more serious fights than this one and they turned out okay. Anyways, my brother is having a bad day for obvious reasons, and he looks like he is about to cry. He tries to hide it but he does a bad job. So we were eating cake, and singing happy birthday. My mom and dad avoid eye contact and then after a little while, he goes upstairs. I thought she was going to go up there to comfort him but nope. She went to her room and shut the door like she always does. I sort of feel angry at my mom for not trying to fix things with my brother or my dad. Anyways I try to lighten the mood but I don't know how. My big sister is playing games with my little sister right now, I don't think my brother is ready to talk to anyone. He says hes fine but hes not. I tried to talk to my mom about random stuff but she seemed tired of it, so I left. When I tried to talk to my dad he just ignored me. I don't know if he heard me or not but it kind of hurt my feelings. It made me really sad and now I want to cry. I really hope this is over by tomorrow. Should I get involved? Or would it make things worse? If I don't get involved will it get worse? Should I wait till tomorrow and then get involved? What if I don't get involved and something really bad happens? Should I check on my brother? Or play games with my sisters. Should I just stay in my room and distract myself? I don't know what to do.