What should i do?????

my cousin will be coming over and they will be bringing their dog!!! i lovveeee dogs but theirs is not trained, all he knows is "sit" (which he only does for a treat) and he is soooo spoiled!!! they give him treats for no reason! alll thheee time!! its soo anoying! and he bit my cousins ear, and tore this girls jacket and bit her! he jumps on you and stuff and does nasty things to your leg!!! he also pees everywhere! and i cant not go to my grannys cuz i have to see my family! help!