I sold my car to a friend..

I bought a new car for myself, and sold the old one to a friend for $400 less than i could have.. (she needed it for her and her bub)

Anyway she now owes me money, and hasn't made a payment since her first one a month ago.

I understand that having a new baby is expensive, but I need the money now, and told her we needed to set up a payment plan if she can't pay in full..

She had a massive go at me and said o was selfish and needed to open my eyes to the struggles of a single mother..

I know its hard being a single mom because I am one, there isn't a contract or anything set up because it was a private, and I know she won't give me the car back, how do I make her pay me? Or have I just lost $1000?