Police reports are very important, as they are written documents made right after the alleged offense has occurred. Basically, they are written down right after the crime has happened, so many details that may otherwise be forgotten are put down for future reference.
In this case, as long as all of this was written down as you say it was (accuser lied, admitted the scars aren't from you, etc.), then the case should go your way. It never hurts to have extra evidence, if you have any, though. Anything that can potentially help you, or that can counter his attacks to your case is something you should bring in.
As for the leverage part, I couldn't tell you as I don't know what is exactly in the police report, as well as what his case will be against you. However, like I said before, if the report has what you said in your question, you should be fine.
An important question that will be asked to the accuser, which you can think about how you want to deal with, is why they waited until the inflictions became scars to tell the police about it. In fact, I really think that would be an important part of the case, and if you can really get the judge thinking your way on that one, you probably have the case won.




