I would be as supportive of him as I could; make him his favorite meals, think of little surprises for him, etc. and work on reducing costs if you can, etc. You can't decide for him that you are the problem and that he should/will/won't leave you and worrying doesn't help you get better or him in any way!

Worry mostly about you and getting better and that will help him feel better too. We can only work on ourselves not those around us.

Sounds like you might be able to improve things with talking with him too; did you discuss quitting your job with him or was it a "surrpise" to him? Talking together on how to make things work in your marrige would probably go a long way to reassuring you and he both that things are going to be okay.