I am so very sorry to hear that her spending is so out of control. I'm going out on a limb because I don't like giving advise, but I'd suggest cutting up all cards and canceling the accounts so no further charges can be made. Call a credit counseling group to help you negotiate payments. I so hope you can get this handled... .I know what a position it can put you in.
I agree with Rocky, I have dealt with all sorts of addictions and there is no soft negotiating your way out of this. The means have to be removed abruptly, she cannot be allowed the facility to supply her own need. It will create far too much stress and self control overload. This would apply whether it is spending, alcohol, gambling or drugs. It will occupy her mind completely.
Of course how you go about it will depend on her own degree of accountability and recognition of the problem. In all likeliness you may need the help of an addiction councilor as it will be hard on you, you will be under pressure, of that there is no doubt. But if not now it will build into greater collateral as the consequences compound.
The addiction will likely switch to something else the trick there is to channel it away from destructive things. Addictive behavior is their structure in a world of chaos, hence to remove addictive behavior altogether is to remove structure. The first task is to contain it before utilizing effective therapy to learn alternative ways of structuring their life.
It is a bit like heroin addicts going on a methadone program, it is still an opiate addiction but methadone does not create flow on destructive consequences. Once some kind of stability is achieved the addict can start to be functional again. From this place it is then easier to deal with the underlying addiction issues once the other dramas are off the table.
So step one: stop the access and means
(stop)step two: refocus the obsession/addiction somewhere less destructive
(contain)step three: professional therapy help to learn better ways to cope.
(repair)
