IF it tore that easily, this may be a case of a quilt whose time is done. What if you were to give your friend a couple of alternatives. Would she be happy with a pair of pillow shams made from the least damaged portions of the original? What about artfully cutting out a portion and framing it for display on the wall?
I have to say -- I've had some older quilts that I liked for sentimental reasons and which I tried to repair. However, once the fabric starts to decay, it's a constant and ongoing process of fixing and repairing, and at some point, it's better to make and enjoy a new quilt.