Find your safe space, wherever or whatever or whomever that is, and rest there often. Voice your fears, concerns, failures (which are probably more like "failures"), frustrations, and angers. Say them out loud to someone who will listen without judgment. Don't let those things fester and rot inside your soul. Get them out and get on with your day.
Why had I let her meltdown, allowing her to cry and lose control of her emotions instead of just reading the book in the first place? Was I trying to be a firm-hand parent? Saying no for the sake of no, so she would learn she doesn't always get her way or what she wants? I don't know, but I felt awful the entire time she slept.