I must admit, I am confused:
The "friend" asked you to finish a quilt and she would pay for it. Then when you quoted her a price, she flipped and basically pulled out of HER obligation to pay. Yet, you say that you are "stuck with a UFO" which suggests that you have the unfinished quilt in your possession. What did I miss that could possibly give you a sense of disconcern.
She pulled out of her obligation to pay, so you should not feel one moment of concern when you pull out of your agreement. You were going to finish it for a price. No money no work. I'd give the UFO back. Simple as that. If she's a friend she'll get it. If not, no great loss either way.