If it really wasn't fun for you, and it makes you miserable and stressed just to think of doing it, and it's not school, and you don't want to stay in France that much longer, I don't think it's that big of a deal for you to say, "You know what? Maybe this isn't for me right now."

To me, the mom sounds like she might eventually turn into someone you resent. I mean, think about it. Could you really get along with someone who is so anal that she'll probably undermine your job the entire time you are trying to do it? It doesn't sound like it will be a good situation for you, especially with what you dealt with last year... I think the problem with taking care of other people's kids and houses is that you may need to discipline the kids, or take care of some household thing, but it's really awkward to do so when the parent/homeowner is going to be there to babysit you. I would be afraid to do anything, because the other adult in the situation might not agree with or like what you are doing.