Do i owe her money....?

my sister let me borrow $100 and she told me to pay her back, and i was gonig to , but, what happened was i got a new job offered and the baystting jobs i had lined up coincide with my new job so instead of giving my shifts to someone else , i gave those shitfs to her, so she is making the money i would have made. and w/out me giving her those sits, she wouldnt be makibng the money she is making, so she making more than 100 in those sits, so should i pay her back the 100?