What sort of Depression were you diagnosed with? General or Accute? If it was accute than you need to have a doctor give you written confirmation that you are alright now. Good luck on that, you best find a doctor that is gun friendly or you may be screwed. If it was General then you will need to be on a prescription to regulate it most likely. I am almost positive it was accute depression, which means it was brought on by circumstances instead of being a chemical imbalance in your system.
I think what is going to happen here is you are going to have to get some therapy and go on a prescription for a while, and get a lawyer to get it all settled. I would seriously speak to a lawyer before you do anything and see what they say.
I am pretty sure since you admitted yourself to the hospital you are not considered unfit. You would have had to be commited against your will for that and been diagnosed mentally unstable. Then again I am not a lawyer, we have a few here though, maybe one will chime in.
I do know for a fact though that I have been in the hospital for accute depression and suffer from general anxiety. It in no way effects me in purchasing or owning a gun. It doesn't even come up when they do the check. However it is not informantion I would offer up while buying a gun either. In most cases the only things they are checking for are felonies or domestic violence issues. Your medical history is private and should not come up on a basic background check.
I wish you the best of luck, but I agree with some of the others. You should have never mentioned hurting yourself to a government agency. Of course you know that now don't you
.
Good luck and let us know what happens.
Paul