If it went down as you say, I suspect your attorney can get the charged dismissed. Your friend's probation does not extend to your home, though his presence in your house (unbeknownst to you - which I know I would not believe) does cast doubt on your deniability.
I suspect the report by the officers' will contain a little different account o fthe event.
But, consult local counsel and see what he or she has to say.
- Carl

