While I'm glad to hear you were finally able to release some pent up feelings and might feel a little better after a bit for the crying, I'm sorry to hear the details of the situation.

Some adults never grow up. Some never learn how to communicate without acting out.

You are obviously old enough to decide whether you can continue to be in this situation or not? If you can't take it anymore (and I don't think you should) why not walk away and limit your time there?

Don't take responsibility for their poor actions. Don't step in and "rescue" them... I doubt they need it. They haven't only fought when you are around to break it up Maybe by having an audience they fight worse? IDK.

Work to make your own personal life a better one than theirs. That's in your own best self interest TC!