well if he thinks he's old enough to slap me I'd slap him back.... and tell him for every action there is a reaction.
The kid wants control so you can either give it all to him or take it all away.
He wants to be an adult, I say give him a week as an adult. He has to do everything by himself. Cook his meals, wash his clothes, get himself to and from school and not help him at all and everytime has asks "mum can you do this..." I'd say "sorry you want control you do it yourself and before you get angry at me remember that I have to do it all myself too... you wanted to be treated as an adult here you go... and don't you dare come back at me with "but I'm a child"
this kid has obviously been given too much by mum and now that she's given him all this freedom and lack of control when he was younger, it's coming back to bite her when she does try to exercise some control. She must have always been soft and a bit of a push over and the kid knows this, now that he is getting bigger and starting to scare her, she's trying to be the tough mum and he's not understanding the change in her so he's acting out even more from confusion and anger.
my other alternative would be to send him to school and whilst he is there take everything out of his bedroom except his bed and his clothes... he will have to earn back everything he owns through correct behaviour. If he wants his television back he's gonna have to ear it etc etc