Miserable at new nanny position

I started a new nanny position a couple months ago. The parents are extremely nice and supportive of me - let’s me eat whatever, have meals with them, borrow clothes, gives me food they don’t want, etc) but the kids have been so exhausting. Cursing at me “dont touch my shit”, telling me to shut up, yelling at me, slamming doors, not listening to 99% of my requests, making rude comments towards me “you don’t know shit” “I hate you” “shut up”. Just now I got 2 of those comments: “you don’t know shit, stop bothering me, and shut up” because I asked him to take a shower before he went on his phone (new house rule). I follow a behavior plan for 2 of the kids but not much helps. I’ve expressed my exhaustion and difficulties working with the kids while they have been extremely rude to me and the parents have apologized and done a lot to make sure I’m okay (I think they’re scared I’ll quit) but with the kids, nothing has changed. Whenever they are rude to me in front of the parents they make sure to tell them to apologize to me. I told the one parent I’m willing to stay and see how the new behavior system works but that I can’t continue much longer like this. It’s been 2 weeks and not much has changed. They act like this to the parents too, however not much consequences are given (behavioral plan is extremely lenient).

I feel terrible, I really don’t want to let the parents down but I feel so sad/ frustrated at work sometimes. Is this normal? Should I just take the disrespect? I know they’re kids and they have behavioral issues (some of it due to previous trauma) Any advice on proceeding?