Don't care if it's petty, I enjoyed watching nmom get treated the same way she treated me

My sister graduated! With honors, she sacrificed her social life for that so I've been telling everyone. The whole family even flew out for the week to see her graduate and celebrate. Lately I had been kind of nervous about it though because it meant I had to be in the same room as nmom, who I haven't seen or spoken to since going NC in January. I've been trying to hide it, but I'm not a great liar and while most of the family is on my side, nmom hasn't been taking NC well and I knew she would probably try to interact with me.

Last week ngranny summoned me to her house because she wanted to make sure I knew that she wouldn't let nmom be mean to me. Ngranny is for sure an N, I've seen her say and do some rather wicked things, but she's always been loving and supportive to her grandkids. Ngranny gave me the pep talk I needed and assured me that she would have my back, which is her way of saying I love you, since she doesn't do hugs or say any variation of the word love.

At the graduation nmom sat like ten people away from me and didn't even look at me, so at first I thought I might not have to deal with her. Also, omg guys she wore her graduation gown from like the 80s to my sister's graduation, complete with her own special honor cord draped around her neck, no cap though. She wore a formal ball gown to my graduation so it was surprising to everyone when she showed up in it. Many people stared, I'm sure nmom thought it was because of how impressed they were, lol. Anyways, after graduation we all went to this fancy restaurant where as soon as I was alone, in the restroom, nmom appeared and cornered me "wanting to talk." She never really wants to discuss anything though, she only wants to berate and belittle.

So nmom cornered me in the bathroom, and began by saying that everyone didn't agree with me, and that it only seemed that way to me because I'm mentally ill. She's been convinced that I'm mentally ill since I was like 10, and she just says "mentally ill" as she's never actually tried to assign me a diagnosis or anything. It all started when nmom decided I was done with toys at the beginning of fifth grade and when I didn't stop crying about her throwing all my toys away, she began telling me and everyone else that there was obviously something wrong with me mentally. She even made me see a therapist from age 10 to 22, although it was a different therapist almost every year because as soon as the therapist even suggested that nmom may be the problem she fired them and got me a new one.

Ngranny knew what nmom was up to though and followed her, and before nmom realized what was happening, Ngranny had cornered nmom in the bathroom telling her how she is the mentally ill one and how maybe nmom should be in therapy. For some weird reason nmom thought I would defend her, so she looked so betrayed when I just hugged ngranny and walked away, leaving her there alone with her own mean nmom. They stayed in the bathroom for like ten minutes before rejoining the table. Ngranny then made nmom publicly apologize to me and everyone else at the table for her inappropriate behavior. Then nmom stayed quiet and everyone else had a nice time. Nmom had also taken off her gown, but kept the tacky purple cord draped around her neck like a weird last minute scarf.