I used to let "friends" walk all over me in the same way. I didn't have courage to speak up, not wanting to cause ruffles and offend anyone. Believe me, the first time you do it won't hurt at all. You will feel sooooo much better once you return the quilt, explain what needs to be done on her part to finish it for another quilter, then let her be on her way. Don't back down. If that destroys the friendship, you don't have much of a friend in her.