AITA for telling my dad’s wife she’s not my baby’s grandma?

Me (F24) and my boyfriend (M26) are finally pregnant after trying for a few months (yay). Naturally we told our family’s about our great news, expecting a happy response. My parents are divorced and my mother has been remarried for over 17 years. So we firstly told my mother (future grandma to our baby) and she was so happy and excited about it. When we told my dad, whom I don’t have a great relationship with, and his wife since 5 years back, his wife, let’s call her Ingrid, directly assumed she would be our baby’s grandma. I politely said that she would not be a grandma, because that space is already filled by my mother and my boyfriend’s mother. Ingrid did not take this well and she said that we should be so lucky to have HER as a grandma to our kid and that she hopes we will regret our decision. I might have gotten a bit triggered by this and told her that she barely knows me, and his not really tried to make an effort to know me and therefore she certainly would not in any way be a grandma to our kid. She stormed out of the house and I have not talked to her since this.

I don’t get it because my mother’s husband (who I grew up with and have lived with most of my life) did not at any time assume he would be called grandpa because in his own words “I’m not your dad, so why would I be your baby’s grandpa” AITA?