Not quite the same but my bf (who's a CM) used to get paid by SS to mind a little girl as her brother had SN and the parents couldn't always cope. There was no judgement on the parents, it was the best way to deal with their difficult situation. Little girl was happy, parents were happy as DD was happy and it helped them keep their family together.
I hope you can get the help you need essbee, there's nothimg wrong with needing a break. No one can go on nonstop 24/7.