Ooh. Good point. I have a level one caution for being in possession of a police HAT which has resulted in significant hassles every time I have a DBS check since.
I think that crimes committed overseas are not included but you Defo don't want one of those so check this out properly.
If the girl in question has gone home then I don't see how you can defend yourself. Unfortunately the Germans are very strict on drunken brawls. You will have to face the music. Tell the truth and rest assured that their legal system is very robust and fair.
I feel sorry for you. It sounds like...