My parents are always fighting and I don't know what to do, I'm an only child so I feel alone?

trust me, you are not alone, i know how you feel...
Try and talk to them about it, tell them how it's affecting you, let them know that you love them so you cant stand to hear and see all of the fighting. Do you have any friends or other family members that you can go to when they fight or maybe just take a break from it? If you can hang out with your friends often and have a good time with them it'll take your mind off it and give yourself a break... But please tell your parents about this when they are calm so that they dont worry where you are and get you into trouble... I really hope this helps!
You can also ask that you can see someone just to talk it all out (like a psycologist) or even a close friend or other relative... <(^.^<)