Find a solution to keep your current job untill you can find something else. Have you reached out to friends or even other parents that use the same day care? Surely someone you trust can take them for you.
Unfortunatly I am in the same position as your boss. I've had to lay off 2/3 of our employees and move our A team members to other jobs, etc. We even have office employees working on our assembly line. We have cut hours, cut our salaries, even instituted a food bank program so our team members can eat!!
The reason why I bring that up is because your boss sounds like a schmuck. He definitly could have handled the situation differently. He probably can't change your hours, etc. However, he could have done it in a more acceptable manner.
Do all of the managers at that company deal with employees like that?? If so, they need to change!!!
Here's another idea, can you drop them off at an employee of the day care's house?? I used to do that with my daughter. They would even take her home if I worked late. Of course, I had to trust them 1st!!!
Good luck...