Girl! You need to talk to your Dr about depression!!! This sucks!!
If you don't start talking to your husband and telling him that you need to have a change, then it will only get worse. Many times people do stupid things out of fear....your fear right now is what? Why are you not communicating to him just how bad it is for you? You NEED to talk to him. You also MUST talk to your dr about getting on some meds for depression or find a therapist that can help you get out of the "blues!" You are NOT alone!!!
My husband hates change too. However, he is at the point where he is VERY unhappy with his job and is ready for a change. Now, for him - that could a few months or longer - it's a slow process for him unless he's forced into it.
How great it is that you have a close relationship with your MIL!!! We often here horror stories!! How great this is!!!
Have him update his resume. Then research the job market like you did before and submit his resume for consideration. let them decide if he's the right candidate for the position. It might be the best thing that happened to all of you!!!
In regards to your inhome child care - you need to make sure that your parents know you are contemplating a change when you send his resume out...they need to be forewarned that you may be leaving them without a child care provider.
If you have enough children in your care - consider hiring a helper to take some of the stress off - you are already a business so having an employee will make your life a tad bit easier!