Echoing what Rohag said: Wow. Is it possible that you could get everyone into family counseling? It sounds like there are some *deeply* ingrained dysfunctional family dynamics going on there. It also sounds like everyone is stressed out and taking it out on each other...no one knows how to deal with their emotions.

Sounds like some house rules are in order, too. It's never too late to institute house rules, but expect a *lot* of resistance and heated emotions. Things will get worse before they get better. You'll have to come up with consequences, too. I don't know how easy that will be for you

Sorry I couldn't be of more help. I hope things get better for you soon