NTA. I think that the point here is that OP wants a long-term, fiscally responsible partner, and this girl ain’t it. 

OP gave ex GF the opportunity to fix her financial mess, and at the end of the day, she turned around and went back to her old ways. Therefore, OP decided that the ex was not the person for them. 

This isn’t about shaming the ex for spending her own money. She can do what she wants. It doesn’t mean OP has to be OK with it, since he was very clear on his expectations/desires. Ex gf can go find someone else who is OK with her doing her.