My (27M) girlfriend (25F) said something really weird

My girlfriend and I were hanging out at her place last night. We were having a normal conversation about random topics, and then she said, kind of out of nowhere, that she wishes she could "fuck" a dog because she's "curious" about what it would be like. She then went on to describe a hypothetical situation where she would do it in front of me, with a "well hung" dog, and in front of a mirror so she could watch. I was in total shock, and didn't know how to react, so I just kind of laughed it off and said that I'm not interested in doing anything like that. <br><br>She immediately got defensive after that, and basically told me that I'm a prude for not being willing to experiment with her sexuality, and that I'm ruining her "fun" by not being more open-minded. She also said that I clearly don't care about her or making her happy, which in turn made me a bit defensive because I feel like I always try to be supportive of her.<br><br>We eventually dropped it, but now I'm really confused and don't know what she meant by that or what she expects from me. We've been together for about two and a half years, and everything has been great up until this. I don't know what to do or say to her now because I feel like she's pushing some boundaries that I'm not comfortable crossing, and I don't know how to communicate that to her without upsetting her more. I'm also really concerned about her bringing up bestiality because it's so out of character for her and I don't want her to do something that she'll regret later.<br><br>TL;DR: My girlfriend said something about fucking a dog and wanting me to be involved/watch, and I don't know what to say or do because I am very opposed to bestiality and this is out of character for her.