You have some time to research, so look into the hospital they're recommending. Get acquainted with the name and phone number of the Client Rights officer. If you get mistreated, document everything - time of occurrence, who did it, who you reported it to, what they did to help if anything, etc. If mistreatment is constant, hang out near cameras and be prepared to speak with a lawyer after the fact.
72 hours of mandatory stay is the general ideal but the average actual length of stay tends to be around 5-6 days for reasons of legality, logistics, and healthcare provider liability.
They may ask you to sign a document indicating that you are voluntarily rather than involuntarily committing yourself. You will feel like your rights are being violated and browbeaten into this if they're very aggressive about it. Sign it anyway. This keeps the commitment off your records for background checks and reduces the amount of time you might have to stay by avoiding the need to present yourself at a court due to involuntary commitment.
If you're absolutely miserable after day 1, play the game they want and take the drugs they tell you to take until you're out of the hospital. You can throw the bottle away afterwards if you want, but the more resistant you are in treatment the longer they'll want to keep you. Lie as much as you need to about your mental state, but don't oversell it.
