Of course this is upsetting; that part is completely understandable.
You have every right to tell your parents: it upsets me when you argue
Whether they use that information to stop arguing, or take it elsewhere, or start to yell at you, is in their hands.
You can also get up and walk away. Got a phone? Call a friend. Take your schoolwork with you. "I'm going to Justin's house to study and we'll get pizza tonight. I'll be home at 9."
(or something similar to that)
I can't promise the fighting will stop but at least you don't have to be in the thick of it, which is an incredibly unfair position for your mother to have put you into.