My sibling has been there for me through thick and thin. She helped pay for my college, bought me things I asked for as a kid, and even let me stay at her place rent-free while I was studying. She always tries to help me, and I’m truly in her debt—something I very much want to repay, but life keeps getting in the way.

She speaks her mind and often says rude things, but I usually try not to let it get to me. My partner has pointed out how she tends to insert herself into our lives and doesn’t hold back her opinions. I try to explain that I owe her so much, and that she just cares deeply about me.

I was about to get married to my partner, but again—life got in the way. She was diagnosed with cancer, and since we weren’t getting the medical attention we needed here, we made the decision for her to go abroad to stay with family where she’s getting better care. The downside is that it’s all out-of-pocket, whereas here it would’ve been slower but free.

It was already a difficult decision but my sibling keeps saying they we are stupid for doing that and how she would have gotten better treatment here. It might be true but my partner’s health was deteriorating and the closest appointment to make sure she had cancer was 2 months away. Whereas, back home her treatment started in a week. My partner had a dog before we met, and naturally I’ve been taking care of her. I don’t mind—I love our dog. But my sister constantly makes comments about the dog. Some of it is true—the fur does shed a lot, and her place doesn’t allow pets—but I’ve never minded any of that. She complains that I don’t visit because I always have the dog with me, and that the places she wants to go aren’t pet-friendly. She says I care more about the dog than her son. But I love them both—my dog and my nephew. I pick him up from school, babysit when they need, and play with him.

Still, she’s been telling me I should get rid of the dog. That’s something I would never do. My partner trusted me to take care of her companion, and honestly, the dog is the only thing keeping me grounded right now.

Fast forward to today—my sister wanted to go shopping, and the stores were pet-friendly, so I brought the dog. She started right away with the same comments, saying I should get rid of the dog because it’s expensive. I tried to stay calm, but then she started accusing me of abandoning my family for my partner and the dog. She said I’m thankless and ungrateful, despite everything she’s done for me.

At that point, I lost my cool. I started screaming. I don’t even remember exactly what I said, but it was along the lines of, “What has the dog ever done to you? Why do you keep attacking my partner and my dog when they’ve done nothing to you?”

It feels like she wants me to repay my debt to her by constantly serving her. If I had the money to pay her back, I would’ve done it already. She does a lot for me and the family, and I try to be there for her too—but I feel like she crossed a line today.

My partner says my sister is toxic, but I’ve always brushed it off, telling myself “it is what it is” because she’s always been there for me. Still, the things she says make it really hard. She’s already been through therapy, but nothing has changed.

I fear that she will eventually cause a rift between my partner and my family and I would hate for that to happen.

I don’t know what to do. AITA? Should I apologize to her?