CPS would throw the book at you. You had plenty of time to consider what you did and you still assaulted him. A friend of mine was being assaulted so I stepped in and put a stop to it by grabbing the guy - we ended up falling to the floor and wrestling a bit when he then spat in my face/mouth, it took all my control not to choke the guy to death and ended up my just giving him a light tap across the chops. Cops got involved and said I was lucky he wasn't pressing charges as I would be seen as the aggressor, allegedly me getting involved in the first place could make me out to be the bad guy and hitting him ranks higher than him gozzing in my face.