Who gets the dog in a breakup?

So we were given a dog as a gift from friends who couldn't care for the puppy. Of course after our breakup those specific friends are going to be in her side and not mine and say gave her the puppy not me. However, I have paid for all the medical bills, food, damages, training, toys, and treats. Shes saying she wants the dong and she has rights to the dog even though i've paid for everything. Do I not have the right to the dog? Even though I live in a house where she can run around and she will be living in an apartment.