AITAH for still “co-parenting” a cat with my ex?

My previous partner, “Victor” (29M), and I (26M) got a sphynx cat 7 years ago, a little while after we moved in together. I had never understood those ‘my pet is my child’ people until we got him, and now I’m like, oh… that’s actually my son. I get it now.

Victor and I broke up due to outside circumstances. We have remained friends. We both agreed that Cocoa should stay at his apartment. I was the one moving out and we wanted to keep things as stable for him as possible.

He and I have still been in each other’s lives, so I go over and help out with Cocoa when he needs me to. I’ll stop by the apartment and feed him to keep him on schedule if Victor’s working late. Sometimes I’ll just go over and see him.

I recently started seeing someone. I told her (27F) in advance that this was a non-negotiable for me, that I’m friends with my partner and I won’t stop seeing Cocoa. She was fine with it.

Lately, it’s become a point of contention, though. I feel like since I told her up front that this was happening, she can’t change the rules now. She feels differently. I’d like an outside perspective. AITAH?