Opposing viewpoint here
You had no problem with her mothering abilities when she moved in with you and left the kid behind did you?
As to the rest,I'd imagine that being in a strange new place,trying to get her money act together and dealing with a new,live in relationship might have been more than a little overwhelming.
Also,you say that this woman did make headway on her debts and did make an effort at contributing fiscally to your joint bills.
Painting her as an out and out user deadbeat seems rather unfair.
Relationships are gambles,I'd rather such a person moved out on their own to clear their head rather than simply staying with me because I'd made them feel gulity,like they owed me their life or something.