Imo, get your needs met first with the extra money. If you need food in the house, buy food. If your clothes are falling apart or don't fit anymore, then buy some new clothes. But maybe to reduce the feeling like you just spent a ton of money on something for yourself instead of her, you could go to thrift stores etc and buy clothes from there just to fulfill the functional side? Use it as a buffer. You can even set aside part of it for therapy sessions, that way you feel like you still used the money for therapy and you didn't spend it elsewhere right after getting a discount.

Just an idea~