First and foremost, thank you for your honest opinion.
As DnJ suggested, I took some time to think about what to do best in this situation.
First of all, I think about my children. Do they like being alone with him for a whole week? No, they don't like this. Do they like to spend a whole week with me in the house, including him. No, been there, done that numerous times, they don't like that.
Secondly, I think about myself. Am I happy to leave my house because he comes to visit and absolutely wants to stay in the same house? No, I don't like that. Am I happy to stay in the house with him for a whole week? No, I don't like that.
So what's the best decision to make here? Simple, there is no right decision. There is no decision we can all relate to simply because you are with someone in your life who thinks only about himself and there is no way you can change or alter his mind.
I decided to look at it differently. He left the house 6 months ago and he comes and goes as he pleases. He does this because he has to come to maintain a relationship with his children. Is this sincere, no, he does this in order not to be portrayed as the bad one by the family, the friends. In his mind, leaving your wife, OK, that's between 2 people, leaving your kids, that's a whole different story, and he knows it all too well as his uncle did the same and the whole family hated him for that.
As always said on this forum: If something doesn't work, stop from doing this and try something else. Well, I'm going to do this. Whenever he came home for several days in the last 6 months, I was always there for him. As kml says, "she just becomes the maid for his visit." That's exactly how I see it as well. He always counts on me to arrange everything. This was already quite the case before MLC, it is now 1000x stronger.
So now I don't want to give in to what he wants. The evidence is there, it turned him back into a monster. He just needs to feel that I can't be there for him anymore. Will this change the situation? Most likely not. But for me it will be the 2nd time (1st time when I put him in an apartment last year) that I once did not give in to his manipulative and controlling behavior.
That is why I have decided not to stay in the house. It will be a very difficult time but I think it will be the best decision to take in a very bad situation.