Stubborn MIL

I am so triggered and fuming mad. Why MILs always very stubborn and will never listen to us. Im staying with my MIL, they have 4 cats. All have their own behaviour. Will pee, poop and even puke on the floor. I am very particular about my 4 months old’s hygiene and health as he falls sick quite easily (esp when he’s attending ifc). She was holding my baby and my baby’s pacifier fall on the floor. Me and my husband told her to not use it and leave it, take a new one. She just wash with tap water and shove it in my baby’s mouth again. So my husband told her again dont use it but she ignore. Wtf is wrong with her ? Just wash with tap water can clean dirt and bacteria meh esp when cats always do business on the floor. AND THIS HAS HAPPENED MULTIPLE TIMES! Im so effing pissed she will never think shes wrong shes always right. Exactly the reason why i hated her and sometimes i dont even want my baby to go to her.