You are not a failure as a person or a mother! Your kids will be fine. They #1 won't starve cause you fed them late and #2 they obviously knew mommy needed to rest and they behaved since nothing happened. Kids can sense this even if they are young.
So glad hubby came home for you. I know you must have fought yourself with asking him to come home. I would have too but sometimes just having someone around makes one feel much better.
Please, please don't get down on yourself. This is just a bad day. Tomorrow is another day and you are doing the right thing with checking with the doctor about a new dose of medication. He will fix you don't worry!!!! This time next week you'll be feeling much better. Just give yourself some time and some slack!!!!!