Kind of toxic mother?

I need some advice to know whether I am over reacting or if what I’m doing is reasonable. Growing up I feel my mother was a very toxic person in my life and I still feel like this to a certain extent although she’s less crazy now than she used to be. Growing up she was emotionally and verbally abusive. Some examples are even as young as 10 years old I remember trying on bathing suits and her telling me that I looked fat in them even though I was never overweight, she would yell and scream at me when she got frustrated like at the top of her lungs to the point her face was distorting, she talked down to not only me but everyone around her including her spouse, her mother, etc. She would do things that I remember clearly happening that were bordering abuse when I was a child like holding me down and force feeding me if I wouldn’t eat something but if you asked her about it a few days later (I remember telling her once how scared I was) she would go into denial and act like it never happened and you were crazy and imagining things. She would say crazy things like once before I was sexually active and had chapped lips she told me quite aggressively that it looked like I had herpes. She also just had very toxic view points that she expressed out loud in front of me like she was always TINY but would stand in front of the mirror talking down about her body, calling herself fat, she would say things to me like boys only want sex and that’s all there is to them (which I feel is completely inaccurate and a huge stereotype), etc. So nothing like horribly abusive or physically abusive but she just had the most toxic viewpoints and was just mean and bitter to a child for seemingly no reason. She also said stuff to me as a kid that when I think back on it now I’m just like “who in their right mind would say these things to a child?” So anyways now she has two more kids who are both under 6 years old (there’s a 20 year difference in age between me and my next sibling) and I have my own children too. Ever since my oldest was born she’s been asking to take her alone and have her for sleepovers and stuff. I am totally uncomfortable with this because I’m still not over the way she treated me as a kid and to be perfectly honest I don’t want to leave my kids alone with her and have her potentially blow up on them or tell them something ridiculous and fill my daughters mind with thoughts of being fat and other ridiculous stuff. I am very careful to keep my temper in check around my kids and I also don’t say any body shaming comments even about myself in front of them as I feel it’s important that kids don’t grow up hearing that stuff all the time. We usually visit her once a month for the day and I am present the entire time so it’s not like she doesn’t know her grandkids at all but at least then I’m there to supervise things and make sure she’s acting reasonable. She still does some of the things to my younger siblings that she did to me as a child. I haven’t seen any of the really horrible things but I’ve seen her get frustrated to the point she screams in their faces while i’ve been around and she still talks down to everyone around her in front of her kids. She’s also just rude and immature, if someone says something she disagrees with she’ll roll her eyes at them and sigh and is just incredibly immature for an adult. Even these things that i’ve seen make me uncomfortable leaving my kids alone with her. She’s never done anything directly to them but I’m not confident that she won’t have one of her moments if left alone with them. She constantly makes me feel guilty about not letting them alone with her and says that I’m not letting her have a relationship with them but I disagree. Like I said she still gets to see them about once a month, I’m just there too. Sometimes she gets in my head though and I feel like I’m being too harsh because tons of peoples parents do worse and they just forgive them when they get older. Am I being unreasonable? Would you leave your kids alone with someone like this? Sorry that this is so long.