Seems to me the issue here is not the value of the bird vs the cost of healing her (you already explained- she’s not worth much), or the act of being kind to an animal (you’ve already made the attempt to help out the poor creature). The issue here is the attachment to a “beloved pet,” as you call her. You and your family members are really the only ones who can figure out how great the attachment to the bird is and how much money you are willing to part with.
There are indeed starving people in need of money, as another poster pointed out, but you have the right to prioritize and set yourself a budget that includes provisions for pet care, or other forms of leisure or entertainment. I wonder if the poster who is so concerned about others going hungry would fault your husband if he bought you a dozen roses, a new piece of jewelry, or a game for the kids.