(((((hugs)))))
I am glad he is quiet at home so far. Please do all you can to make sure that you do not drive him anywhere alone. Not for quite a while. It simply is not safe for you, for him, or for anyone else on the road or walking near the road. If that means he doesn't get to go somewhere, it is a natural consequence. Safety has to come first.
Your therapist needs a sharp smack upside the head, and some video of what difficult child is really like at home. For reasons that make zero sense to me, many tdocs and psychiatrists etc.... think that we are exaggerating or inventing when we tell them about our difficult children' violence toward us and toward home. They are often 'shocked' to see video or police reports about the problems because they didn't think things were 'that bad'.
That male nurse did you zero favors. The chances that if difficult child lashes out iwth violence again that he will end up going straight to the adolescent psychiatric unit are very very slim. MAYBE if he is violent within 24 to 48 hrs of coming home then this will be reality. MAYBE. But probably not. When difficult child realizes that he will probably get a night or two at the psychiatric hospital and then he will go home again, he is going to feel that you can do NOTHING to him. The situation will be even more dangerous at that point.
Why do I think they will not admit him straight to the psychiatric unit if he waits a day or two to explode? Experience. been there done that with Wiz, and to get him placed anywhere took a very real attempt to kill his sleeping sister. Later when he was 'just' headbutting me (cause that isn't like he 'really' hit me, just ask both husband and Wiz, grrrr) and attacking me, it took refusing to allow the cops to leave with-o him, refusing to bring him home when he got kicked out of the youth shelter, and the judge issuing TWO direct orders to the deputy to write up the incident formally (given during 2 separate court dates a week apart) and STILL we couldn't get a police report, ANY documentation from the police or the court, or any psychiatrist/therapist to take us seriously. The psychiatric hospitals were more of a place to go to hook up with a girl than a place to get help. We spent time at all but one with an adolescent unit and NONE of them would keep a child more than 2=3 days, and most stays were under 24 hrs.
I really hope and pray that where you are they will keep difficult child if he harms you again, but I don't think they will.
I think you need to start making police reports every single time he hurts you, threatens you, pushes you, or shows any violence toward you or anyone else or your pets. The police will not take you seriously the first few times. They see a LOT of parents refuse to press charges, or deny the violence really happened. Your difficult child is not going to stop being violent until the consequences are very serious and very real. Of course he needs help, and therapy and whatever the psychiatrist thinks will help. Sadly, until you have shown more than a few violent physical attacks, and called 911 for help, no one is going to do much to help your family. Admission to a psychiatric unit requires a LOT to get insurance to pay, and for many programs that might help you cannot even think about being accepted unless the court orders it.
The violence MUST stop. You have to start calling the police to document difficult child's attacks or else you won't get the help for him that he needs so badly. Yes, it can make you feel like an idiot, a bad parent, etc... when the police come out. And nobody wants all the drama of cop cars in the driveway, etc... But unless you are willing to do that, your difficult child is just going to become more and more violent until he reaches the point where he is in so much trouble that he cannot live in society for a long time.