employers worst possible reaction to pregnancy

I've been a professional Nanny for a family for 3 years with two girls aged 4 and 8. I potty trained one. Taught the other to tie her shoes and ride her bike. I'm with them 60 hours a week. Today was my 11 week appt and ultrasound and decided to let them know today that I am pregnant but would love to continue to watch their kids in my home( which I have before but usually am at their house). She replies with congrats but we're going to let you go after this month. Not what I expected or planned for. I am the bread winner between my husband and I. Screwed over doesn't quite capture how f***** I am.