Your PARTNER is not your wife, and has no claim on ANY of YOUR money. MOST particularly, she has absolutely NO right to tell a person mired in bad debt which she has not repaid, that YOU will lend her money. Because just like her other debtors, YOU will not be repaid.
She was quite wrong to mislead her own mother. She was quite wrong to promise money that was NOT hers.
Obviously the apple hasn't fallen far from the tree. You might want to give some serious thought to a trial separation.