Crazy family is making things so much worse! How do I tell my aunt and uncle to watch what they say?

So, growing up I was so so close with my grandma (94 now) She was my best friend, my brothers too. I lived right next to her, we have a lot of land and my parents built on it. My gma gave my aunt and uncle land to build on as well. (Gma on dads side) My dad has 2 siblings, sister and brother who are quite nutty. Aunt is a self centered raging alcoholic and uncle is alcoholic/pill popper and his wife is downright horrible. My whole family lives in like a 6 mile radius in the country. I have 3 other cousins (on dads side) and a brother who helps me tremendously but he’s only 19 so he’s also busy a lot. Almost 10 months ago my grandmother had a stroke, we had grown apart because when I came out of high school she was very mean to me. Lots of memories coming back to me now of those times. Now that I’m older I can see how people are, a good and bad thing :( so I was a preschool teacher I loved my job so much but I got Covid so I couldn’t see my gma after the stroke for about 3 weeks or so till I got better. Then my dad, who had pushed so hard for my gma to come home even though his siblings wanted her to go to hospice, really wanted all of us to chip in a day of our free time like we did in the hospital, she comes home and suddenly nobody is available. My brother and I take on all the work, I quit my job and my brother works for my dad so he can help me when I need him. So I was there during the days and my aunt was there at night. Along with my uncle and my aunt who would clean my gmas butt and make a huge deal about it, why I have no idea it made my grandmother feel bad and they would all talk crap about her on the porch and she could hear them, beyond messed up. So many things happened that I was not happy about when I would come relieve my aunt in the morning. Elder abuse for sure to cut the story short. So, I offered to move in and do 24/hr care so it would be less work on my aunt and uncle and less taxing on my gma. Also, my gma suffers from chronic UTIs which I just got under control finally about 3 months ago. Thank the lord. So I’ve been living here doing the 24 hr care 7 days a week -8 hours on Saturday my mom takes over for me and 2 hours in the afternoon on week days my aunt cooks dinner for my gma (might I add she only cooks stuff that my gma can’t eat then gets mad that she won’t eat it and throws a fit) for about 5 months now, caregiver for 9 total. My gma is getting dementia, not totally bad but it’s getting worse I can tell and my aunt and uncle do literally everything you’re not supposed to with a dementia patient. They try to make her mad/sad and then she takes it out on me when I get home. Attacks me on all my insecurities and makes me feel bad about all the things I care about most. My fiancé lives with us, without him I couldn’t do it. She likes him a lot but he’s Mexican and I guess she’s a little racist. Of course I know she had a stroke and dementia so I let it go. I don’t try to argue I just reassure or deter the subject. Which used to work so well but not anymore. How do I tell my aunt and uncle to watch what they say? They’re so crazy they can’t even have a normal conversation. I’ve tried to politely tell them before. So has my dad but they just turn it into a huge fight. My fiancé and I are going kind of nuts bc my immediate family and him are the only sane people in this situation and it’s so hard to handle all this. Everyone tells me to leave for my own sanity but I just can’t leave my grandma in the hands of these nutty people. My dad is also going through a lot right now and he needs me to be his constant. I want to be here for my gma and my dad so so bad. But it’s really getting to me. I’m 24 and planning a wedding, diving into planning actually because it’s the only thing that gets my mind off things and makes me happy. So sorry My thoughts are everywhere, it’s not all bad but my family Is so disappointing. I’m tired, there’s so much else too these people have made my fam (& gma) miserable