How to handle narcissistic attack, possibly demonic. What can I do to get this person to let me and my kids go. I’ve tried everything but he won’t let go

I’ve been attempting to divorce  an extremely controlling abusive partner for the last seven months. I tried to do it in the kindest, most amicable way possible, but this person just will not let me go. He refuses to sign any type of settlement agreement and he’s doing everything he can to prevent this from moving forward into an actual divorce. He’s now threatening taking my kids and taking all of the finances and the properties. I am having trouble getting clear guidance on what I should do. I’ve felt frozen for the last eight months. He doesn’t wanna let me go, he’s using this control to stop me from leaving and I just don’t know how to break loose at this point