You seem like a very caring person who wants to do the best for your pigs. You took her to a vet, you enquired about the best thing to do and did everything you could. None of us, even those who.have had many pigs for years, can keep them alive forever however much we desperately want to! You are doing the very best for Ziuta now by actively looking for a new friend for her. Dont punish yourself for an illness that you didn't cause. Look forward and keep enjoying your pigs, I'm sure you will have more in the future!