It is unfortunate to have this kind of experience; but, as mentioned before, while there are legal contracts signed and a service-monetary exchange it is purely business.
But, somewhere along this lines; we caregivers know that for us is not just matter of business, we get involved emotionally we grow and support with each child that passes through our lives and also with their families.
In cases like the one that took you by surprise; you must learn to turn to your own and you'll see how blessed and fortunate you are, feel happy that, life did not choose you to hurt others as this family did to you (imagine all the pain and frustration they're going through).
Don't take it personally; I think there are people that cannot handle this kind of situations properly or at least weren't ready for their lives to fall apart.
It is true; in gratefulness to the many years you've helped and supported this family, they at least could have had the decency of letting you know in advance but that is life, sometimes it throws you a bad hand when you weren't expecting it.
If you believe in kindness and humanity then also, believe that life gives you wonderful unexpected surprices.