Should I allow my child to see her grandma?

I need some opinions on an issue I’m having. My mother in law is toxic. She constantly called me a bad mother, tried to physically assault me, and threatened to call CPS on me for “starving” my child. Even went as far as to say she would record/take pictures of my daughter to back up her ridiculous accusations. Of course nothing ever ended up happening because my daughter is a well behaved, happy child and showed absolutely no signs of abuse. Her father and I broke up because of all the stress his mother was putting me under and I also felt like he wasn’t listening to me. She was over the moon when I was out of the picture because she got to see her grandchild every weekend when her son had her. I had no say in this so I ignored it as best I could.

It’s going to be a year in two months, I’m now back with my child’s father and we’re living together. He cut her off because she was threatening me all over again for no reason. I’ve never done anything for her to hate me. It was like she thought my daughter was hers from the get go and all I did was stop her from trying to control my way of parenting.

Anyway, she hasn’t seen my daughter in half a year. She keeps calling my boyfriend asking if he can go visit her with our daughter. He’s respected my decision to keep her away but I know it hurts him to know his mom won’t ever see her only grandchild grow up. He’s forgiven and forgotten about everything she put us through even though shes never apologized and at this point, it would mean nothing to me. But am I right to hold onto this grudge I have? Should I let him go visit her with our child? I’m conflicted if I’m being toxic myself for keeping my daughter from seeing her grandmother because of how nasty she’s been to me.

I’m genuinely only afraid that by letting her see my child again, I’m giving her access to continue her toxic manipulative behavior. When she’s in the picture our relationship is shit, to put it simply. Ever since we cut her off, it’s been amazing. No fighting, no anger, no worrying about him showing me text messages from his mother degrading me. What if she never changes? Am I doing right by keeping my daughter away? What would you do?