I am a very involved stepmother, have been for 20 years and raised my stepdaughters in my home. I don't ever call them stepdaughters, and am only using the term for the sake of the story. I have a teenage granddaughter (via stepdaughter). My mom texted me saying that she thinks my brother's son has a crush on my granddaughter. I replied "they're related," to which she said "they're not really related." I responded that it was offensive to say my granddaughter is not really related and that I do not want my mother to come for the holiday. Some background: she has a long history of textbook narcissistic parenting behavior, and this happened right after a major family event. She usually creates issues around positive family events. She has made little comments about my daughters not being "real" over the years. She is not close to my nephew: her comment was not based on something she heard, it was based on watching them interact at the event. Am I overreacting and am I the asshole for cutting her out of spending the holiday with my husband and my kids based on the remark?