Hi,
I am so sorry to read your problem, your obviously at your wits end.
I dont know if this will be any help, but i find that a bold chair or a time out helps really well, dont speak to him when he is being bold and lead him to the spot that you have set out as "bold area". if he keeps coming out just keep leading him back. you may have to this fifteen times at first but he will soon learn that he is getting no attention for his behaviour. start by giving him a minute for every year he is old. Consistency is the key. Ignoring a childs bad behaviour lets them know its wrong. Even slapping is giving him attention and kids thrive on it whether its good or bad attention they are getting.
dont allow the other kids to laugh at his antics either and maybe set aside some time where he can be your little helper, and praise him for everything he does right, over do the praise if you have to and he will eventually see that being bold doesnt get him anywhere.
