Working in mental health is always going to be challenging and the post made by the OP illustrates exactly why.
Ultimately treating people against their will is not ideal. It's not ideal that people are effectively incarcerated against their will and ostensibly 'for their own good' because it feels almost inhumane or cruel.
The reality is that this is the only logical choice: you are administering a medicine with the intended and genuine aim to help keep the patient safe and ultimately, this will keep your other patients safe and more to the point, to keep you and your team safe.
Having worked in secure psychiatric care settings, I can tell you now that unless treatment is commenced and then maintained, a lot of people in such services will never leave them.
These kinds of mental health conditions are complicated and need a great deal of time and skill to resolve effectively. Some might argue there is no effective cure in many cases. I am no expert in that regard but I have seen people get better. They do somehow grow or adapt to live with whatever condition they might have and will eventually, with the right support, walk out of those front doors and get back to living life.
Being a nurse such an environment is tough. It's probably one of the most demanding jobs in nursing, actually. You have a level of responsibility that would be expected of nurses in the emergency department or critical care but possibly without the same level of medical oversight in some cases.
Look after yourself. First and foremost. That is basically the only real advice I can give you.