AITA for “killing” my girlfriend’s cat that I didn’t know about

Honestly not sure what to do in this scenario. Throwaway account since she knows my reddit but probably will find this soon. My girlfriend (26) and I (27) have only been really dating for a few weeks (6ish), Our relationship has been wonderful so far but turns out she’s been hiding something? We both have no pets or so I thought. I love animals so i’ve definitely talked about pets and animals with her multiple times incase we move in together. She always said she never cares much for them but would be supportive if I ever got one. Heres where this all fell apart though. I went to pick her up for a date, went into her apartment with a bouquet of flowers, lillies to be exact. For some context the apartment didn’t have any toys, scratch post things or any proof that a cat had ever been there. She was in the kitchen, but left the door unlocked when I got there. So i set them down on the dinning table (dumb mistake in hindsigh) and went to greet her. We talked completely normal and we both headed out, I showed her the flowers (this is important). She thanked me and said they were beautiful and just set them down again and we left. Nothing much happened on the date, went to dinner had a nice time, dropped her off and went home. The morning after my phone had 20+ messages plus 6 calls from her calling me an asshole who was cruel to animals. Turns out her cat was in pain all of last night and has passed in the morning. Now im not an expert in cats but my little research says this timeline is a little short but i’m not too sure so not much comment on this. But basically she wants to meet up so she can ”tell me to go to hell”. I’m honestly really confused on what the actual situation and story is. She has NEVER mentioned a cat, or any pet and we’ve known each other for a year as we’ve been in the same frien group for a while. Am i in the wrong? Do I work this out, can this even be worked out?