I mean, acute care and the emergency department are both connected. I just happen to live in an area where public mental health is particularly bad. With regard to you, you are right, the adult mental health system is not the best. Unfortunately by now, as you have found out they tend to use it as a sort of containment zone, particularly for regional areas where they lack sufficient beds, and where those beds end up being occupied by prisoners, people with addiction issues, extreme cases of psychosis, and anti-social personality disorders.
You're probably going to both like and dislike what I have to say but unless your behavior is so severe it endangers your life they're probably not going to admit you. You seem like a person who is suffering from anxiety which also leads to self-harming behavior. They have to weigh up the pros and cons of it and work out on the basis of all of the things I've told you and your condition whether an admission is actually worth it for you, what problems it would cause, and whether it would resolve anything...
Being admitted to a psych ward is a bit like swimming around in a fish bowl, you don't know any of these other fish, and the environment is completely foreign to you. It can also be quite traumatic particularly with anxiety seeing some of the things that you may be confronted by which can lead to other things such as PTSD as a result of an admission.
So you have to weigh up the pros and cons. Can you manage in the community? If not go to your nearest hospital or call an ambulance on 000 straight away. But you may find its actually more beneficial to you in the long run if you can find someone who cares in the community to look after you for a while.
I know how difficult it is. You're more than welcome to call SANE during business hours or LifeLine/Beyond Blue/Suicide Callback Service if you need extra support.