First off you have my prayers for your health issues. I pray that you have the best possible care and outcome.
Secondly, please protect yourself and your children. It sure sounds like his violence is escalating. Call the cops each time. Leave the house if necessary. Stay safe!
See an attorney is a good first step. Laws are different every of course, but if the insurance is in his name, he can be compelled to maintain the insurance along with paying alimony and child support, attaching his wages if necessary.