Thanks for the replies; and I do sympathise with all younger referees in such situations. All I can say is that, having experienced some nasty matches some years ago, I didn't quit and have now gained a sort of resistance. There will inevitably be difficulties in the future, but dealing with them becomes second nature and you begin to take things less personally.
I didn't know about the mandatory hearing either: to me it doesn't seem right that a referee who takes the proactive stance of abandoning when necessary measures have been tried can expect further repercussions, whereas someone who struggles on to the end not only feels terrible, but gives the offending club(s) a free pass. I expect in my brother's case that the home club will probably give information on his behalf and take the matter into their own hands; as I've indicated, he is part of a club programme, so may be outside regular county procedure.