UPDATE: Stepmom calling herself grandma??

I recently told my father that we are expecting. News I’ve been waiting to share for 18 weeks, as the first trimester scared the piss out of me. Well, as soon as I did my stepmom started calling herself grandma, even though and yes this was years ago, I made it clear if I had kids of my own they wouldn’t refer to her as grandma. My mother and my husbands mom is grandma. My stepmom has been in my life since I was 4 but we don’t get along well. I tolerate her for my dads sake. This is a pretty known fact. I told her to choose whatever name she wants but is still referring to herself as grandma... HOW DO I HANDLE THIS????

Update: this woman is NOT my mom. I literally just view her as my dads wife. I have zero emotional connection with her and if I could just see my dad and not this woman, I would. She treated me horribly as a child and I refuse to even allow her to be alone with my children. She hasn’t earned the title of “grandma”, my kid/s will have two grandmas as it is. If you think me not wanting my kids to call an evil woman grandma is shitty then you have a lot more coming to you.