Norianxx,
You are not the MLCers parent. They are an adult. If your adult child - I'm not talking 18 years old, but 40 years old or so , came to stay at your house for a while would you do that for them? Hell no. You'd expect them to pull their weight. You might cook a meal, but you'd probably expect them to do the dishes afterwards - or at least offer to.
If she's not contributing to the household chores then I'd be inclined to do pretty much nothing for them that they can't do themselves. I dunno, I haven't got an at home MLCer, but if I did, and their room was a mess I'd shut the door as I walked past so I don't have to look at iit - like a teenager, and let them wash their own clothes and cook and clean up after themselves, unless there was a planned family dinner or something,
If you don't want a divorce let them sort it out, in life if people really want something then it's up to them to do the hard work and get it sorted.
Put your focus on you, and your kids. It's really hard in the beginning to get that, as you're used to being a we, but the rules have changed, and so has the game. If she asks for help and you feel like it's appropriate to give it then do so, but I'd err on the side of letting her do a bit of the heavy lifting herself. But I think you kind of know that given how you worded your question.