You staying is so much more damaging to the kids than you leaving.
Especially considering this heartbreaking fact:
They idolize him even though he can be so cruel to one child in perticular and it breaks my heart!
And the fact that by sexually harassing and abusing you in front of them, through unwanted touching, he is teaching his own to act in the same way:
He is constantly touching my bum and boobs to a stage my DS is 11 and he starts doing it now!
What happens when your son does this to girls at school? Or to women? He's being taught to behave in a sexually inappropriate and dominant way due to his fathers behaviour and your acceptance of it by staying.
I know that's hard to hear but while you're absolutely a victim of a terrible man's abuse, you have the choice to leave but your children don't.
You need to do the right thing for them, not keep them in an abusive (emotionally and sexually) environment because you don't want them to think of you as the bad guy.
They won't long term as they'll see their dad for what he is and more importantly, them liking you shouldn't be more important than them being safe.
He's never going to put them first so unfortunately that means you have to do so.
He's teaching your son to touch women inappropriately and being especially cruel to one of the kids. Aka bullying them.
You seem numb to the level of harm this is causing them.