AITAH for telling my mother the truth?

Hi Reddit! Last week I (29F) told my mother (61F) the truth, which something I normally refrain from doing. I never thought I would be having teenage level drama with my mother at this stage in my life, but I've brought it upon myself after 29 years of learning how to deal with her.

A little bit of context: growing up, my mother has always been on the narcisist side of things. She yells when she doesn't get her way, she's hipercritical of everyone and often cried to get me and my dad to do everything she wants. I know it stems from family trauma, so I've spent my life both resenting her and trying to acommodate her. I left home at 18 to study and I have been fortunate enough to not need to life with her and my dad for extended periods of time since. However, at the end of 2024 I had to leave my job due to severe burnout and moved back in due to my financial circumstances.

This last week has been hell in the house. My mother has been yelling everyday because my dad is taking care of his mother (who is in the hospital due to a broken leg). She hates my grandmother. She hates even more that my dad doesn't between the two of them. So, it has inevitably led to arguments, crying fits and yelling sessions. I try not to set her off, but I'm not perfect. I don't agree with her behaviour so it becomes hard to keep quiet. Last week, she told me she wants to divorce my dad (a common occurence) and asked me if I would leave him as well and go with her. I had a momentary lapse of judgement and answered honestly: no, I would not go with her. My thoughts were that I just came from a tough situation with burnout and my dad is the sole provider for the family (I work part-time and she doesn't work), so he seemed the safe and stable choice. She was quiet and apparently ok with my answer.
Last sunday she was yelling with my dad and things moved to me. She told me I was the worst kind of human because I told her that I prefered my father. I didn't tell her that. I told her that I would stay at his house. I explained that to her and told her my motivations. She screamed I was selfish. So selfish that i only liked my dad for his money. She also said that I was her worst mistake. Had she known I would turn out so selfish she wouldn't have had me. I apologized for hurting her and told her that I was only saying what I felt at the time. As hurtful as it was for her, my only thought was to tell her the truth of what I felt. I was (and still am) trying to find my footing after loosing my life as I knew it. She told me I was dead to her. I apologised again for making her feel so bad. She doubled down and told she never thought I was capable to be so meanhearted as to choose my dad over her. I (stupidly) told her I never thought my mother would tell me I was dead to her after last time. Her answer: if I made her feel like she wanted to commit suicide (its a recurring theme in her yelling fits) then I was dead to her. I left it at that because I was emotionally drained.

Today she woke up calmer, which is never good with her after a fight. She has used every single opportunity to call me cynical and selfish, even going as far as comparing me with criminals that mistreat their family. I know I hurt her. I also know I could have just shut my mouth and not answered at all when she asked if I would leave my dad with her. And, logically, I was selfish: I was thinking about my well-being above everything else. I also tend not to tell her what I feel, which isn't fair of me. I'm also very literal so I often speak on what I think without contemplating the consequences. On the flip side, it's not the first time she called me selfish, a mistake or told me that I was dead to her. The previous times where for different reasons, mostly because I didn't agree with her or didn't do what she wanted (one time it was because I forgot to make dinner when she was expecting it). At this point, I don't know how to feel about it. I feel like I'm losing my mind. So Reddit, AITAH for telling her the truth? (PS: I may be an unrealible narrator because I'm telling my side of the story. I know I am the villain in my mother's story, should she tell it, the same way she appears to be the villain in mine).