As frightening to the free world as it is, I was actually a mental health counselor for a number of years in a state hospital (free treatment on the side ).
It isn't pretty, but this will work for you if you can be alone with her to do it with a perfectly bland face when you do it
Next time she gets that urge to splurge, you look her dead in the eyes and say with quiet, whispered intensity like you do with a big secret:
"You know, they didn't keep me there for years because I saw things, but because I didn't. I'm still convinced it was my research into proving that penguins can speak English that got me here. Penguins are shifty with it and you actually have to catch them at it on a reliable visual recording device. I never could alone, but now, with a person they recognize as sane the Penguins will trust and the authorities will believe me....we can do this! Have you been to Antarctica? No? Hey, it's worth the job,career and institutional commitment...this will be my third time with shocks and drugs, but it will be nice to have company."
And when she freaks out and calls someone, you just shake your head sadly and ask them, "Is this the drinking again, or is it the crack thing, this time.?"
It will only take you about 30 seconds and she'll leave you be after that, I expect.