Oh no, what a horrible situation to be in.....what makes it harder is that you are trying to help your friend which is evry nice of you and im sure she appreciates it but you do not have to tolerate this kind of behaviour from another person's child.Can i ask when he does spit on her or slap her what does she do? Does she discipline him or let him get away with it?
I wonder if it has anything to do with any certain foods...perservatives?? What sets him off, surely he isnt this bad all the time.

It's great that you have spoken to your friend about this and i really hope things improve soon before you do lose it with the little boy. Take care x