Technically, you were defending someone caught in an unfair fight. If you hadn't done anything, you would get hauled in on a good samaritan law of some sort. Sure, you may have have taken further than 'defense,' but you can't be held accountable for how you react wen a drunk man attacks a female friend of yours. If you had it all to do over again, you probably would've had stadium security get involved before it got to the point where you had to get all spider monkey on his ass.
There, i wrote your non-apology for you. No admission of guilt whatsoever.