You're too hard on yourself K! Sleep deprivation doesn't help anyone's patience and your boys are super smart, they know how exactly to push your buttons.
I'm a strict parent, I have rules that Jack knows are definitely not to be broken, but at the same time I am quite relaxed about some things (making a huge mess etc is ok but the rule is he has to clean up).
I guess I can be quite scary though because I can make my point or get my way through either just changing the tone of my voice or even just giving a certain look. Yelling doesn't work with him at all.
If you want to try and change it up, maybe get super quiet with them and see how it goes, might scare them into doing the right thing?