I (26f) got invited to my grandmother’s 83rd birthday dinner at a Mexican restaurant. This is my grandmother from my mother’s side of the family.

I have an aunt (50f) from my father’s side who also got invited. Her and I have some problems, but I thought we were going to set aside our differences and be civil for this dinner.When my aunt first got into the restaurant, she instantly took my cousin’s drink (they are not related and this was this first time they have ever met each other) and took a sip from it. Then she wanted to take a sip from my drink and I told her that I don’t share drinks (which is something I don’t ever like to do anyone). Afterwards, my aunt got upset, saying that all of us are family and that we should share drinks with each other. I ignored her and took the straw from my cousin’s drink because he wasn’t aware that someone else took a sip from it. My aunt found out I did this and made a comment about how alcohol naturally kills germs in straws. Then she proceeded to take a sip of everyone’s drink at the table to prove a point I guess. I started to get progressively more irritated with her as the night went on. My aunt was making snide comments to my relatives about how I was unemployed (currently looking for a job) and how I am not going to meet a man who wants to be with me (because I am in my mid-twenties). She says that I am wasting my youth and that it was embarrassing for me to live with my parents rent free at this age. For context, my aunt is single and lives rent free in a nice studio apartment because her own mother (who happens to be my grandmother from my father’s side) pays for it! At this point, I asked her to repeat what she had to say about me. She gave me the dirtiest look and I kept asking her to repeat herself. Everyone at the table was telling me to shut up and to not pay attention to her, but then out nowhere she called me a fucking loser. I told her to go fuck herself, and I got escorted out of the restaurant by my mother who told me I was out of line. When we got home, everyone told me that I should be mindful that it was my grandmother’s birthday. That I should have swallowed my pride and not engage in this kind of argument. They kept saying that it was beneath me to stoop to her level. Despite this, my aunt and I got into another argument. I called her a fifty year old loser, and she called me a spoiled brat. We started yelling at each other and this prompted my grandmother to start crying. My whole family is blaming me for ruining my grandmother’s birthday dinner. I apologized to my family, but I didn’t apologize to my aunt.

AITA for arguing with my aunt in the first place?