There is no 'healing' the disorder he has, (did aka dissociative identity disorder) there is a way to cope with it and to make it so that one can be in charge and so that there can be communication between the two identities, but there is no 'bringing the two into one' or 'making one go away' or anything like that. Hopefully he will learn to switch alters (what an identity apart from the origonal is called) healthily soon.