I wish you and your brothers the best, it is sad to hear that your parents are putting you through this. I too, have been through a divorce and I did my best to leave the kids out of our disagreements and arguements. She did not. I got custody of my children. The kids were old enough to KNOW what was going on. They also supported me and thanked me for Not using them. It made a big impression.
So my suggestion would be: If they continue to use you all, then all of you or at least the oldest should set them both down and tell them in your own words that They are supposed to be the Adults and setting and example, and that ya'll refuse to be sucked into the arguments and made to choose sides. Remind them thay YOU are old enough to remember All they Say and All they Do and how they are trying to use ya'll to pick sides. That you will remember their immaturity and which ones showed the most LOVE...
Sad that you will have to be the responsible one to open their eyes...
Best Wishes...