I have been there too, even though it was a male friend whom I gave lots of money and time to help him, his community and his family after a natural disaster. He turned on me one day, and I still don't know what I did wrong.
It can be hard, but the only thing you can do is move on. Investigating a situation or having someone intervene in a situation will give you more mixed signal, false hope and prolong the heartache. It can also be hard for us on the autism/AS spectrum, but forget about this person and put more prudence and energy to the other strong relationships that you have with people.