Before we get into this I want to say that this is obviously not a preferred way of doing things. That said, if matters at all to you that you will get into trouble for it then you probably won’t be able to go through with it.

Be aware of the consequences
The legal stuff, the fact that you have basically ruined your reputation (even if the guy was a notorious dick), those are all, obviously, inevitable. The less obvious part is inside your head. You spent your whole adult life up until that point eating shit and then you exploded, you can't ever know if you would or would not do that again. It was a loss of control. It is easy, at this point, to have your whole life spin out of control, have all your addictions and potential addictions get the best of you. You don't feel as if anything is in your power anymore. On top of all that it feels like it's your fault, even if the bastard had it coming for years before that.

You will be blamed. No matter how bad it was for you punching your boss, throwing him/her out a window or down a flight of stairs, will not make you sympathetic. If you bitch about how bad it is to your family and friends you might be able to milk a little false sympathy, but tackling the problem in the most straight-forward way is frowned upon. People will use the situation to feel better about themselves, all the times they took shit and did nothing about it will make them feel like they are more disciplined and sensible than you.

Note, also, that if you win the fight with your boss he, if he is a guy (and often even if it's a woman, but not always) will have to destroy your life in order to soothe his/her ego. For a man who sees his position at a place of work as an emblem of everything he has achieved with his life, being physically humiliated by an underling is not a small thing. He will not rest until you understand, once and for all, that you are the lesser.

If you do do it... (Note that this is not suggestion)
You may want to make it count. Do not stop halfway though it hoping that an apology will make things better. If you say something bad you might as well keep going with it, say something else. if you throw a punch, throw a bunch more, and some kicks. Make them feel the full extent of your wrath. It's not as if it will alter your position much. You will likely wind up in jail even if you don't. If you are going to get the death sentence for one thing, you might as well get it for four or five.