Beat the Crap out of Someone

Hey, I have a little bit of a problem...  Really, it's more of a fear of a problem I MIGHT have in the future...

See, a few days ago this doucher I work with was calling me names and shit to me and my friends.  I couldn't say a word without him busting out with some asinine comment, it's like he was actively gunning for me for some reason.

Well, anyway, long story short, when we were all walking out to our cars after our shift was over, he finally just stepped over the line.  I really feel bad about it, I mean, he's just some kid with insecurities trying to feel better about himself, but I just snapped and really let him have it.  I headbutted him in the chin (He's about a foot taller than me, and more muscular), then punched him in the face.  He went down, completely caught off guard (I wasn't prepared for it myself).

Anyway, I was still pretty pissed off at this point (I must have anger issues myself) and stomped on his forehead while screaming "I AM NOT A FUCKING *name he was calling me... don't remember now*". 

It's been two days now, and I haven't heard anything about it, though I know he's OK, he doesn't even look beat up.

I was wondering if I could be charged with anything, or thrown in the metal clink should he choose to press charges.  I mean, he really had it coming, but he never hit me back, and we're both over 18.

How should I prepare for such a fight?  I'm very good with blunt instruments, like bats, but they're pretty hard to hide at work.  I'm thinking about something small like a pocket knife, but it's too small, things like that always get knocked out of my hand before I can do any damage.