His reaction to you merely saying that you living together tells me everything I need to know.
You are separated. You separated due to emotional abuse(?).You are not obligated to him.
You owe it to yourself and your children to keep a distance for that reason alone.
If he moves in you will be his carer and whipping boy by the looks of it because, you know, he’s dying.
Now that sounds callous but it isn’t. Not really. I have sympathy because his illness is terminal. He may be accepting but he could be so angry and frustrated also.
The reality is that he could live on for years. Do you want that? Do you want to subject you and your children to the harsh realities?
He may say it would be in the children’s best interests. I don’t believe it is.
I’m so sorry because this is an awful situation to find yourself in but I would be keeping a healthy distance.
You separated for a reason. It doesn’t sound as though that reason has gone away.
Without the emotional abuse, my answer might have been different.
And he really doesn’t get to let himself into your home uninvited either. 