Terrible to hear all this mate and I can't really add anything that hasn't already been said.
However, your Mum may have a point about your contribution to living. I obviously don't know the situation, so apologies if I have this wrong... just trying to rationalise where you Mum is coming from. Have you worked out how much it would cost for you to get a place of your own (including rent, council tax, gas, electric, home insurance etc. etc.)? If this figure is less than ~£700 a month then you have your sums wrong! If you offered to pay your Mum a lot less than this, then she is naturally going to be annoyed, especially as she will be venting some of her financial situation on you.
As others have said, it's probably time for you to move out. Would you be getting blamed for your Mum's situation if you'd lived elsewhere for the past few years... I'm guessing not.