Phone the housing association and make a start in getting the property in your own name
Change all bills into your own name
Stop paying anything that is his. Car insurance. Phone bill etc
Start a claim for benefits. UC will have an adult element. Child element disability element and carers element and housing element. Turn2us has a benefit calculator to give you an idea of what you are entitled too
You will then qualify for council tax benefit
CMS for child support. You can go on line and do a calculation for this
Start going through the house getting his stuff together in one place for him to take. Move things around. New bedding, paint a wall anything to make it different.
Contact, he comes and takes the kids on x day and x time. How ever that looks to you.
Get support for yourself and the kids. Let school know. And seek out low cost counselling for your self. Journaling helped me to stop reaching out to my ex.
Gather good people around you. This will pass but you have some bumpy times ahead.