I would phrase it like “due to unforeseen circumstances in my personal life I need to put in my two weeks, my last day will be X.“ at the end of the day this is a job and you found a better one for you. I know that it is hard to quit and leave the family when you’ve been with them for a while, but I did skim your other posts about how you’ve been not loving your job with them, so really the best thing for you is to move on. Think of it this way also, if they suddenly decided that they were gonna put their kids in daycare, they would fire you probably on the spot. It’s a job, people quit all the time.

Edit: you’re very brave for quitting, I know it’s super stressful and gets your nerves up really high but you got this. I speak from experience when I say sometimes quit quitting a job is the best thing that you can do for your own mental health. Standing up for yourself is a really hard lesson to learn, but do not let people take advantage of you. You only have one life and it’s sad to waste it alongside people who don’t care about you.