Taking your friend's comments in the best possible way, she might have been saying that she would help you trace the pattern for yourself particularly if it is intricate and will take some time to do it. However, if that might not be the case it will be very awkward as I agree with you about patterns and copyright. It seems to me you have two choices. You can simply tell your friend that you are very committed to design copyright practices and she is putting you in an awkward position by asking this when the pattern is still available for sale and easily obtainable. or... you could take the turtle approach. Work on it out of her sight and if she brings it up again say that you've gone off it for a while. If she gets insistent, tell her you'll sell her your copy and then get yourself another one. Although best to make sure in advance that you *can* still get another one.
Actually I have a much bigger problem with your friend's rudeness in assuming that you will share. It's one thing to accept an offer, it's quite another to insist on a share you have not earned in something.
Just my humble opinion and worth the price paid for it.:-)
Diana