I work as a department supervisor in a hospital, the head of this department is not my manager but we work together…

One of my responsibilities is managing the appointments, he came to me today asking for an appointment for a friend of his, so I told him “the best I can do for the time being is after 9 working days, but I will update you if another patient cancelled but it’s not a promise”…

He didn’t like my response and started to raise his voice, and it wasn’t the first time, so I told him to not shout…

He looked at me in shock and left my office, went directly to the COO and told him it’s either me staying in my position or him, it’s a governmental job and they can’t fire me…

The COO told him to figure this out with my direct manager…

So after few hours, while I was taking my break in peace in the coffee shop nearby, I got a call from my manager to come immediately to his office, and I saw someone from my department so it was obvious that they offered her my position…

According to her and my manager, he called her only to ask about my attitude, which I don’t believe…

He told me to suck it and let it go and best thing to do with that guy is to nod with my head whenever he shouts!!! I explained myself, told him he’s always like this, and one of my staff came out of the room next to my office to check why is he shouting!!! He was shouting loud enough to be heard from another room.

So I told him I can no longer be in the position, it doesn’t come with any other benefits, I’m not getting paid for the extra responsibilities…

He told me that he asked all other departments, no one said any negative thing about me, so it’s not up to me to quit the position even if I want to!!!

Did I do anything wrong by telling him not to shout? What’s the best I can do now?