((confused)) I read thru ur sitch and my heart goes out to you. You def need to set some boundaries. Take care of yourself and ur children. Battling an illness and a M sitch isnt easy and I can sympathize. As hard as it is, you need to stop worrying about him and concentrate on YOU and the kids!
You cant live in fear of what he is going to do. You just cant control him. Once you realize that it does get a little easier. He gave you an STD!!! Are you really going to let him continue to have his way on everything?
You need to be busy. and get busy. Live your own life and not be there at his every beck and call.