How can I leave my boyfriend with my children without actually 'stealing' them while he's at work?

We have a 3yo and 1 yo, have been together for 10 yrs. I want to leave, he wont let me leave with the kids. He says I can go find a place to live and we will work out a custody plan on our own - without any courts involvement. I know, from being controlled by him for the past 10 yrs that any plan WE make will actually be the plan HE makes, and changes at will later. He doesnt want to pay child support, makes six figures, has told me that if I try to get 'one penny' of child support from him he will sue for full custody and when he's done with me I'LL be paying HIM child support, (his words) I only want to split the kids 50% each or close as possible and if im entitled to child support then whatever it takes to take care of them, even if its just help with daycare. He says I wont need daycare cause it wont take him long to find a new girl and she can take care of the kids, I say I DONT THINK SO! I've been staying in his house for a year now but he wont let me actually move in, I just have clothes stashed everywhere he wont even let me use a closet cause he says a closet is for his wife someday. I think thats pretty emotionally abusive there. I dont work, I take care of the kids all day and seldom leave the house, oh by the way we are both in our mid-30's. I dont know how to leave, he threatens to kick me out if i dont 'behave' and says if he calls the police they will put me out without the kids cause this is their home, not mine. I dont want to move out while he's at work and anger him, but i dont want to leave them and then file for custody cause he could drag that out forever, meanwhile i'm without my children, possibly being accused of abandonment. I told him that our state is a 50-50 state and they wouldnt give him full custody anyway, that I'd have to be the devil himself for them to take them from me.. he said I'm sure I could prove some mental illness and abuse, I have witnesses. I asked who? our friends? he said they are not OUR friends they are HIS friends and that he would subpeona my mental health records from when i was treated for depression yrs before the children were ever born. I take good care of my children, it pains me to think of being apart from them, but I cant live with this sociopath any longer. He also says he's the primary caregiver even though he never ever makes a bottle or changes a diaper or has ever woken at night with the kids. I told him a judge would ask who takes care of them all day and when he says me the judge would ask him- she has mental problems and abuses them but u leave her unattended all day everyday with them??? nice try. he says i can behave for short periods, thats what he'll tell the judge. silly.. but he's crazy.