Communication problems

So I’m 13 , I’m mature and know enough about the world that I know it not friendly, and sometimes you just gotta get through it. But I’m having a problem and asking form people who are older than me and have experience. Or are in my parents shoes and how I should approach the situation were you could understand.

So I help my parents out at their salon, they are under staffed and under a lot of pressure and stress so I said I would help out.
All I have to do is take calls and do check out

So summer started recently and that mean more free time right? So my parents ask me to help them again I said yes

So I’m working and of course it not like a only appointment allowed place we take walkins to. But sometimes it so busy and my social anxiety just gets really bad, my stomach starts hurting and I feel very sick. Today was one of those days, it was very busy and I was very overwhelmed. My parents and me started fighting because they kept letting people in, kept not talking about anything to me. So many people had to wait it was just a lot. I felt like I was honing to cry so many times that day and I really started to think if I just left it would better for them and me.

A little context my parents are very hardworking and they deserve much more than they get. But with working almost 12 hours a day they just start fighting so much. I have to watch this as well because I’m with them for most of the week helping out. Sometimes when they fight I just want to hit they so hard they get it back together and try to work it out.

Anyway how do I talk this out? I know that they should fix it but so should how do I tell them what I’m feeling? Thanks so much in advance ^^
Sorry it was so long, probably not good to pour my gust out onto the internet > >