Pet "sitting" For Ex Gf And Her Cat Got Into Something, She Wants Me To Pay The Bill. Am I Responsible?

Pet "sitting" for my now EX GF and her cat got into something, now she wants me to pay the vet bill.

Ill start off with saying I lived with my now ex-GF at the time of the incident. I was pet "sitting" while she went away for the weekend. I wasn't paid and there was no contract. She just asked me to feed her cats while she was gone. The cat in question has IBD and has to eat a certain regiment of food. I had been living with her for 7 months and fed these cats every morning for her without gripe or issue. She left Friday night. I fed her cats as usual and went back to writing papers for college. I passed out late. One of her two cats got into a treat bag ripping it open and devouring them after I went to bed. There were no immediate issues and it wasn't apparent besides lack of appetite from the cat that does not have IBD that anything was amiss. Saturday night the IBD cat got majorly sick and had a follow up vet visit that Monday or Tuesday. Now that we are broken up she expects me to pay the vet bill in full.

Adding this in here; that cat was already sick daily puking and having diarrhea multiple times a day. She's not been doing good anyways.

Am I responsible for this bill?

I live in VA if that helps anyone with any legal advice or otherwise.