The way to do this would be to talk to the police who took the statement in the first place. Let them know what you've said above, that you'd been drinking, was scared, stressed, and confused. Upon reflection, you realize you do not want to press charges. See what they tell you.
It's possible that they may have already turned the matter over to the State Prosecutor's Office. If that's so, there will be nothing that the police can do. You'd have to call the State Prosecutor's Office, ask for the name and extension number of the person assigned to the case against the defendant (give his name), and make an appointment to talk to him or her.
You are the complainant and without your cooperation, the prosecutor can't possibly win his case, so he or she will be willing to talk to you. Tell him how you feel. If he won't drop these charges, you can cease to cooperate with the prosecutor's office. So long as you don't ignore a lawfully served subpoena, you don't have to make yourself available and without your cooperation, the case will ultimately be dismissed.
If you are lawfully served with a subpoena, then you must show up to court when called upon to do so. However, if you don't want to testify against this person, it would be best to show up with a lawyer.