Morning OP. The difficulty with answering a thread such as yours is that there is only one answer. To leave. How you do it, with what assistance, when, what your next steps are, these can all be advised upon and discussed. But leaving is the answer.
Would you have titled your post "How on earth can I manage living with a rapist whilst having young children in the same house?" No. But that is actually what you are asking, and as a pp said, that situation cannot be managed.
I don't want to be alarmist, but aren't you scared for your dc? I don't know you and I feel scared for them, and for you. Whenever a lovely (seeming) middle class professional kills his wife and children all the friends and neighbours are shocked. They say things like they were a lovely family, this sort of thing doesn't happen around here. But it's exactly where it happens.
You mentioned earlier about having to deal with what you've accepted if you do leave, ie having to think why you put up with him. Is that worse than having to deal with what's happening now? Many, many women find themselves with men who they thought were something they're not. It doesn't mean you're stupid, or horrible, or weak. It means you're human, you trusted somebody and you've been terribly betrayed.
What you do now about the situation, whilst it's incredibly hard for you, will say something about your character - mainly because it's not just about you, but vulnerable children.
I know a family where the mother was abused by the husband. He abused their sons but not their daughters. Then one of the sons started to abuse one of his sisters. One daughter eventually told a relative, the dad was arrested and went to prison. It ruined all their lives, one of the sons later committed suicide. The mother knew what her husband was like, but buried her head in the sand. Her daughters blamed her (quite rightly) and their relationship was badly damaged. She died an alcoholic.