My takeaways in (rough) reverse order of importance:
You're not getting your phone back. If you can disable the login remotely, you should do that. Though you phone is probably at the bottom of a river by now.
Don't worry about Facebook Sometimes with social media we can look for patterns that are simply not there. This could be happening now.
You didn't have real friends if they are going to not talk to you now, they were never your friends. It's good that you know the truth now, as much as it hurts. Try to talk to a few of your coworkers, the ones you think you can trust the most. One-on-one is best. Talk about how you're feeling. If they don't care, they are not your friends.
You helped your coworkers You whistle-blowed on your boss, and your boss was doing the wrong thing. You saved many of your co-workers from having to deal with this, and the administrator will have to be more professional in the future.
You protected the patients health There are reasons why there are multiple staff working the hospital at night. Should something happen to you, maybe fatigue causes you to make a mistake, be inattentive, miss something, there is no check and balance in place to protect the patient health.
You protected the hospital. A follow on from the previous point, should something have happened to a patient, the family sued and in court it showed that a person entrusted with their care was sleeping or not even present, the hospital would probably be looking at a large payout. This is especially true if the person not being present meant that the hospital was not meeting minimum legal standards.
You have an ally which is Corporate. You should get in touch with them to see if they can find you placement elsewhere. You can explain the situation to them, and let them know you were the whistleblower. You can let them know you think that they figured out it is you. You should also speak to the fact that you did the work of two people on many nights, and are a hard worker, but cannot work in this environment. Explain that you are hoping to get another chance elsewhere.
What's done is done. You will debate with yourself what you should have done, but what's done is done. You acted with courage, and you are paying a price. It's not fair. But you have integrity.
You're under extreme stress but not all is lost. I know at times it feels like everything is a mess. The administrator doesn't like you, but she can't find a reason to get rid of you. This must mean you're a great worker.
Eat. Even if you don't feel hungry, force yourself to. Now is not the time to get sick. Don't make your body suffer, just because you mind is suffering.
It's time to work elsewhere There is nothing left for you there. You have a lot of good qualities, work ethic and empathy towards those doing you wrong to name a few. Even if Corporate can't help you, you need to look elsewhere.