A lot of women in these situations feel 100% trapped and it's very easy for all us to say ' why would you stay or let this man be around your kids'. But the reality is she was likely terrified to ' disobey' his orders. You heard him per the x saying nothing can touch him. If he believes that and he's able to convey that in a believable way, then people probably are going to fear him. He probably told her if you try to leave, try to tell, try to call the cops, I'll do xyz to you , your family, your kids, etc. Doesn't mean it's right. Just probably how it went. **speculative **
ETA For the record, I'm not saying she's blamless or that she should not be charged with negligence or endangering the child. I'm just speculating why so many women stay in dangerous situations. I wonder what the mother(s)? of his own 3 children have to say about his ' parenting' skills.