AITA for refusing to answer any questions my grandmother has about my sex life after she made a comment about my butt?

I am 22F and my grandmother is 68F.<br><br>For context, I am not particularly insecure about my body and I have a average build. The difference between me and my relatives is that I have a bigger butt. It is not huge, but it is bigger than the rest of my family.<br><br>I recently went to visit my family (mother, sister, aunt, grandma, etc.) for my sister's birthday. While we were all sitting on the couch, my grandmother looked at my butt and said: "You have such a nice butt. Too bad you're a lesbian." (in Portuguese, but I translated it to the few words in English)<br><br>I am not a lesbian, but I am a little shy to talk about my sex life. I usually just avoid the topic and keep my private life private. When she said this, I stared at her for a few seconds and said "Are you serious? I have nicer boobs than [sister] so you should be happy that I have a butt and not boobs."<br><br>I know I was being a bit harsh, but she has commented on my body before. For example, she said to me once that I had a nice legs, but they were not good for dancing since they were too skinny.<br><br>Some of my family members asked me what happened and I told them what she said. I also told them that from now on, I will not answer any question about my sex life and she will have to deduce things from my answers.<br><br>Later, my grandmother asked me if I had a boyfriend and I said that my private life was none of her business. She got mad and asked why I was being so mean and giving her a runaround.<br><br>At the end of the day, I'm wondering AITA?