As the protector, of sorts, of her money, your first obligation is to pay her bills in the obvious manner - her survival first. This typically means her rent, food, medical needs. Then, like anyone, when we have extra, if we have legitimate debts, we pay them. Beyond that, one can spend on activities, vacations, electronic toys, etc.
Here is how SSA explains it:
Your payee receives your monthly benefits and must use the money to pay for your current needs, including
•Housing and utilities;
•Medical and dental expenses;
•Personal care items;
•Rehabilitation expenses (if you’re disabled).
After paying those expenses, your payee can use the rest of the money to pay any past-due bills you may have, give you spending money, support your legal dependents, or provide entertainment for you. If there’s money left, your payee should save it for you.
Your payee must keep accurate records of how they spend your money. Your payee must also regularly report this information to Social Security."
See here: https://www.ssa.gov/pubs/EN-05-10097.pdf
So, technically, if she owes you money, you CAN pay her debts to you. BUT, because it is you and there is an obvious fiduciary duty on your part and could be an appearance of impropriety, you will want to make sure you have PROOF of her owing you. For instances, did you have a written lease when you were paying her rent (her part of the rent)? Was she living with you before the 2 years and paying rent while she was able to work? But not after? This would show you HAD a rental agreement, implied if not in writing, so keep proof of those payments back then. Written agreements are nearly ALWAYS better then "assumed ones", but when there is tons of circumstantial proof of an implied contract, it can be fine. Any proof of statements such as an email where she said she'd pay you back when she won her case, etc. Also, if she is in agreement (and I would hope she would be), she can sign a statement now, feasibly, confirming that 2 years ago, you agreed to let her borrow money from you retirement savings to survive, pay rent, food, medicals, etc. until such time as she could win her disability, at which time she would pay you back on a payment plan to be decided at that time, with consideration of her newer survival need bills. I'd make this an affidavit of some sort with a notary. And keep it, just in case SSA ever questions. Just make sure you are not putting your own debts owed to you before any other debts she has of similar importance - as that could appear to be a true conflict of interest. For instance, if she owes her Doctor, who she needs, don't put your own debt before that, necessarily.
The biggest problem I see is that you say that her bills run you $1000/mo. That implies she can support herself and not drain you anymore, but that there is no extra to pay down debts, (including yours). Yes, her food stamps will likely stop. But at least it means your husband will no longer be supporting you - your daughter's 1000 pays for her while your own draw pays for her. And DH pays for himself. When you say her bills are 1000, I assume you mean her rent - which is going to you or your DH, as her portion of shelter, thereby reducing your own share from 1/2 to 1/3, yes? Same with utilities.