Abusive MIL—protecting my child

My mother in law was and is extremely abusive to my husband. Ever since I met her I’ve watched a pattern of complete emotional abuse. She screams at him, calls him names (says he’s a disappointment and she’s ashamed to be his mother, etc), brings up his dead dog to get under his skin, and literally once OD’d and ended up in the hospital and ADMITTED that it was a manipulation to get his attention and to “see if he cared about her.” Beyond that I found out she was sexually abusive when my husband was a kid... he’s only told me bits and pieces and I honestly am sure there is more but it seems like he has genuinely blocked it out.

Anyway, my husband doesn’t speak to her anymore, but she and my father and law are still married. I have all sorts of grievances with my father in law as well, but not nearly as severe, and my husband really values his relationship with his dad. I really like to support that because he has tried cutting his dad out before and is always very depressed when they are on bad terms.

The issue is, my husband and I are TTC now and I am terrified for my future child. Luckily, they live across the country from us so we only see any of his relatives about once a year. But I still have no idea what to do. I don’t want this horrible abusive woman anywhere near my children. But I just know as soon as I get pregnant the pressure from my father in law is going to start... “it’s her grandchild, you cant keep her grandchild from her, I promise she’ll behave!” etc.

Regardless of how she behaves, I just don’t want her in my child’s life. I don’t want my child to grow up knowing her. I am genuinely terrified of the trauma she inflicted on my husband (and me too, at this point) and the idea of having her anywhere near my child makes me feel physically ill.

Also... saying “leave it up to my husband” won’t be helpful, because he’s equally conflicted. His dad and the rest of his whole family are always on the side of “she’s your mother, just make peace with her!” and we both know that keeping her grandchild from her will cause massive rifts with his dad and the rest of his family, which will cause my husband to be extremely depressed. (By the way, his family is all aware of the emotional abuse these past several years but they are still always in favor of “everyone making peace” even though she’s the one who is volatile. They don’t know about the childhood sexual abuse and I know there’s no way my husband would ever tell them, and they’d probably also not believe it or say he misremembered if he did)

I know he will be torn between “I want to make my family happy, and the child will be fine with very infrequent (like once every year or so) supervised visits” and “I want to entirely protect my child from her.”

Please help :(