River10 - both "adulting" and dealing with mortality is something that many MLCr are not able to face. My own ex refused to discuss getting a will or funeral wishes for herself. She also was, while a trained book-keeper, completely at a loss in managing our own money and credit.
From your first post it would seem that you are familiar with the standard script.
One key thing to remember, this isn't about you and never has been. It is him and his inability to face tough realities so please know that it's nothing you did, nor even your cancer at issue here. It's all on him.
You say "building a better life" - but it really sounds like he's a slow-moving train-wreck. Not paying his bills, not dealing with his responsibilities. You're probably better off not being part of that.
Have you checked to see what legal recourse you may have in getting him to step up at least a bit financially? He may be in such bad shape that he's got nothing. In which case you may want to see about getting the ties severed on your own. Some others may have information on what direction you can go. I presume you are in the USA somewhere since you mention "state"?
On BD H52, W50 T27, M26 S21, D23 BD-9-Mar-16 D-15-Jan-18 Final-19-Apr-18 I am a storyteller. The story may do you no good. But a story is never for the listener. It is always for the one who tells