The worst case senario is prison followed by parole and lifetime sex offender registration. The best-case scenario is acquittal or dismissal. This is a dangerous allegation and one that you need to have the assistance of counsel with significant experience. If you do not already have an attorney, you need to interview several attorneys quickly and pick the one you are most comfortable with.
The crime making a false report requires knowing that such information is false and intending that the officer or agency shall act in reliance upon such information.