Unfortunately this scenario repeats itself so often police press as they did here for a complaining witness to go on record and the prosecutor likewise will pursue the case. You need to consult an attorney to advise you what you should say and do next. You don't want to place yourself in a position where false informing or other obstruction of justice charges could be filed against you. If in fact no crime occurred, but you told the police things happened which did not in fact happen you could be held responsible. If you've simply had a change of heart and don't want to see him prosecuted, that is a different story and you can discuss that with your attorney who can represent you and your position as a victim of crime with the prosecutor's office.