It is sad, nursing is dangerous when on vacation. I have worked in places, that fire nurses, when they return from vacation. At one place, I was told soon after orientation by the staff, never take a vacation, you will find you do not have a job, when you come back. They went on, they start talking about you and since you are not in the building, you are unable to defend yourself, and soon look guilty...unfair, but it happens.
Anyway, I am sorry. You have experienced an injustice and it hurts, a lot. This pain, will last a long time, but you must go through it. Nothing but a correction, will make it go away. Only time. That time is different for everyone, but I can honestly say, it takes a long time. And even then, you will never forget it. All the gimmicks in the world, will not take it away. To be blindsided like that, causes much grief. Surround yourself with loved ones to get you through this. I really feel for you right now.
There is much wisdom in the above post, but it is probably too much to handle right now. So please sit down with an attorney, to do the work for you. I will say, do not resign. They are Not doing you a favor. Just think, they fire you unjustly, but want to do something nice? There is no nice, in business, period. They only do, what is expedient for them. If you already signed a letter of resignation, explain to unemployment, it was under duress. This will nullify it immediately. It was clearly a firing, a force resignation or whatever you want to call it. You are due, unemployment wages and should go forward. Do not worry about future references right now. You are in survival mode and need to take on today, only. Good luck, we are with you, you can get through this and will. Peace!