AITA for telling my grandparents that they are forbidden from taking my cat to the “summer house”

I 14F have a cat names missy. To me she’s like the whole world. Currently I’m with my grandparents because of my moms business trip. We live in an apartment but we have a little house in the hills where they will sometimes go. We used to have to cats and they would constantly bring the kitten up there. On day he just disappeared and we never saw him after that. The cat isn’t the family cat or something it’s 100% mine. My friend got it and I feed her clean her litter box and everything. Now comes the problem I told them that it is ok for them to bring her there with them as long as they don’t loose her. I let her go up there because she needs the fresh air and nature as we live in the city. Yesterday they went up there and when they came back she wasn’t with them. I asked them where she was and they just said they didn’t find her so they left her up there. They did the one thing I asked them not to. They said they waited for 15 minutes, that she didn’t show up and they left. I had a mental break down. There was a really dark time when the only thing keeping me alive was the thought of what would happen to her if I died. She’s the sole reason I’m alive today. I just shut myself in my room and cried. I knew that I couldn’t do anything. In the end they went back up there not to find her but because they forgot their phone. Luckily she was there when they arrived she was sitting on the porch so they took her home as well. I told them that from now on as the cat is mine they won’t be allowed to take her up there because I don’t want anything to happen to her. As I said she means the world to me and I don’t know what I’d do without her. I know what I said might’ve been harsh but she means a lot to me and and I don’t want anything to happen to her.

AITA?