soverylost, you're not a fool to have believed him. You were hopeful. But now you do know better.
And "self-care is not an option"? Really? Who is going to take care of those kids if not you? And how will you have the strength if you DON'T take care of you? The analogy used in Alanon is the one about the oxygen masks in an airplane--when the flight attendants are going thru the emergency procedures, they always tell you to put on your own oxygen mask first before helping others to put theirs on. The reason for that is that you can't help anyone else if you haven't helped yourself first. It holds true in everyday life also, soverylost.
Alanon would likely be a huge help to you now. Many meetings have child care available.