Try not to be too hard on yourself. With these children, our reality is skewed. It's totally insane that when my son is reading, I feel frustrated if he's tired and having trouble, I actually internally scream, "This is so frustrating and you don't even need to be reading, but you insist that we do this!" He gets so upset at the exceptions to the rules. And it's exhausting arguing about the english language with an emotional three year old.
It's just essentially what parents of 1st graders go through with their daily homework routine that for most parents is incredibly frustrating, we are just experiencing it earlier.