((Simon)) I am sorry about this with dad. I really do think that is how dad is and odds are he will not change no matter how kind you keep trying to be. He seems to try to avoid sharing his true feelings and the issues he has with his temper and drinking. Maybe he is lost not just because of the dog but deep down due to mom.
I hope you can find away to get away. Even on weekend trips if need be or stay in your bedroom whatever room he isnt in. The negativity will drag you down more and if you are like me you can do without beating a dead horse