Winnie It is fucking hard living together whilst separating, the hardest thing you will ever do.
I totally understand you not wanting to cause a horrible atmosphere and keep things stable for the DC's sake.
However things do need to change.
You don't need to do it overnight, but start making little changes, if you are usually at home every dinner time, arrange to be at a friends or family members house for dinner with the DC's.
Don't tell him, just breeze back in after a lovely evening out with the kids.
Start just doing less for him without making a huge fuss over it.
Also start living your life, go out one night a week, once kids are in bed, even if it is to a friends round hpthe corner for bloody coffee.
again don't tell him, or make a big deal, just pick up the keys and say see you later, only be an hour, and go, why not do a gym class? Even if you sit in the bloody pub by yourself reading.
Small steps, small things, all add up. You need to stand on your own two feet a little, and not be walked over.
Then by time he does eventually fuck off, you will be stronger for it.