What would you do if your husband called your son a f***ing idiot?

My son is 15. He is a good kid. He gets in no trouble. Just typical boy stuff...not cleaning room or forgets to do chores sometimes. My husband has raised him since he was 2. Husband drinks and does not have many nice things to say sometimes. He called him a f***ing idiot because The blower wldnt start. He screamed it in my face that he was a f***ing idiot. What would you do?