Sorry you are having such a hard time, Cervix. Sounds miserable. Can you make them an allowance for food etc and leave them to get on with cooking for themselves? Also discussion needed about keeping their own pits rooms clean and not cluttering, dirtying everywhere else in the house (washing up their own dishes etc or putting them in the dishwasher, taking turns in a rota for hoovering etc). Then, if they do not stick to the rules, let them have only enough food allowance for bread and cheese. Might mean a lock on your fridge. Sorry, don't have any other suggestions.
Hope you can get out and have some time to do stuff you want to do. How about showing them this thread? (then nc of course).