Hi KarinaM
Sorry I don't have much practical advice to help - don't have any children myself but can empathize as I have an 18 yr old nephew who is a handful. The only thing I know of is an organization in NZ that is a peer support group for people with brain injury. Maybe there is a similar group in Oz. The link to the NZ group is:
http://www.thinknz.org.nz/

I did a quick search for an Oz group with the same name but couldn't find anything - but would imagine there must be a group some where.

Good luck and hopefully one day he'll realize he's lucky to have such a wonderful Mum who cares so much.