Daniel, thank you for the posting and being so candid in terms of what's happening. I am sorry you've found yourself in such a predicament and I can only echo the sentiments of those on here who have already expressed a hope that you find yourself back on your feet in short order.
I think it also - as has been said - provides solid evidence that BA do see the failure of passengers to complete their full itinerary as being an abuse and that they will re-price itineraries based on the sectors actually flown and seek to recover via ADM the shortfall. At the moment I think it's now a question of when rather than if this will be extended from travel agents to individual travellers.