Who’s in the wrong?

My friend found a kitten about 3 weeks old but she couldnt take care of it at the time so she gave it to me to take care of and to eventually give back to her once it could eat dry food on its own well me and the cat have bonded a lot and I just want to keep it ....? Ive taken care of it since it was little its about 9 weeks now i love the cat so much. She wants her back but I don’t really wanna give her back would I be wrong to keep her