#1 she is not a friend a friend would not treat you like this.
#2 you are not in any way obligated to quilt the thing as you never told her you would make her a quilt you told her you would help learn how to quilt.
#3 there is not much you can do about her selling it with the fabric you gave her as she saw it as a gift.
#4 If you let her treat you this way this time she will think its alright to treat you this way another time;
Dealing with people like this is very difficult they are users and are always looking for another poor soul to get to do their bidding. Don't confront her when you are up set write down what you want to say cll her on the phone and tell her"Due to the way the quilt is sewn you are unable to quilt it for her. But even is you could do it you are too busy working on a quilt of your own and do not want to take on anymore projects at this time. (DO NOT ENABLE HER TO USE YOU SHE IS A USER) JMO