Welcome to the real world, and i am not being unkind here. You might or might not have done this, how would i know? What you have to do now is get your act together. The first thing is, no matter how much you are p***ed off about this, STOP FRETTING. Deal with it on, and only on the days comes you can do so, don't sit worrying, get on with your life.
You are not going to die.
Get a solicitor, get in their office and tell them everything, dare i say the truth, whatever it is. You need representation!
Don't think that the cop will have the slightest bit of concern for you, they are trained to do otherwise and as individuals they are incapable of of compassion at a reasonable level, that is why they are police officers and not aid workers.
Stop worrying about jail, unless you act like a nutter, the courts will not intend to send you down.
Let the whole experience be a lesson to you, don't let yourself get into a vulnerable position, always keep in control of your life, don't let some copper have the say on what your future will be.