This is normal thing with us men. Sometimes we feel the urge to look after women or help them. Somewhat the intention is in retrun you will get better sex.
I have done the same mistake. Sent money to couple of girls in Philippines. Even lent money to Sugar Babes. Did I get my money's worth? Not at all.
The lesson I have learnt is some women use the sob story to extract money from you. They may give you the impression they care. But once you refuse to lend more they are gone to the next victim.
As others have said, cut your losses and move on.