^^ Excellent suggestions, especially the food banks.
I think your relatives need to pony up a bit of $ for your food, or stop charging you rent entirely, since they're committing fraud on their own applications by concealing that income. (That business about the fraud is not something you would point out; you just point out that their refusal to help you is making it impossible for you to get assistance, so they need to step up and make up for it. If they're at all snotty about this, you will have to find somewhere else to live, the sooner the better. There should be community bulletin boards at the food banks, and people there may be able to point you to other resources...)
Sorry you're going through this.
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"I believe you find life such a problem because you think there are the good people and the bad people," said the man. "You're wrong, of course. There are, always and only, the bad people, but some of them are on opposite sides."
-- Terry Pratchett, Guards! Guards!