OK, it's OK, you can do this. There is no immediate danger right this second, so you need to breathe and out a few times, and just sit for a moment or 20!
Your goal is to live happily, contentedly in an environment that is healthy, and positive for you and your DC.
Do you have that now?
NO. So what needs to happen/be done to achieve that.
Either he goes or you do.
If there is a risk of violence, then YOU need to be the one to get yourself and your DC ready to flee/go to a safer place. If there is a record of violence AFAIK you can apply to have HIM removed from the home. If you own the home and are married, you are entitled to half of it's proceeds, you may not be able to force him to sell it, but you can put a charge on it, so you get your half whenever it IS sole. You can potentially even stay in the house until the DC are adults/have finished education, but you'll need advice to establish your options.
Speak to WA, speak to CAB, find out your options and entitlements, that will give you an idea of what you are playing with, and also will help you understand what resources you can call upon. Once you have that structure in place it's a lot less complicated. Your BIL is on board, that helps enormously. You need RL support!