I think I didn't phrase it right.
What I meant was exactly that he is not going to change, not while you are with him.
His problems at work suggest that his attitude problems are spilling to work.
So, (what I meant is that) you are better off without him.
By staying you are effectively letting him be like this.
Only if you separate, and possibly him losing his job can he start taking responsibility and possibly change.
Not encouraging you to stay with him at all. Just to be clear. :)