Send her a message that because of her obvious distaste, she’s no longer “obligated” to be at your house for any reason.

I would say, "Yeah, we get it. You're barren. Your coping strategy of ranting against kids is so transparent it's just embarrassing."

Just tell her she's no longer welcome in your home and life, and block her.

She's fallen in with the 'breeder' hating cult on the internet. Cut her off until she comes out of it. Your kids WILL notice her hatred of them and you and internalise it, regardless of whether you think they're too young to notice, they WILL. She's no longer a safe adult and the way she will treat them could be looked at as abusive. If you get push back from the rest of the family just ask them why they want you to expose your children to such hatred and why they think you should allow her attitude to damage your kids emotionally. "Deliberately hurting kids is abuse. Why are you insisting that I allow her to emotionally abuse my children?" That usually backs people off hard and fast. I don't know if it matters or not but I'm child free by choice. My mental health issues would make me a terrible parent so I didn't have kids. There is a vast difference between us and the breeder haters, please don't put us all in the same box. What she's got herself involved in is a sick, insidious mind set and cult that is damaging to both the parents and children they choose to attack just for existing. Cut her off and get very blunt with anyone saying you have to tolerate her behaviour.