Miscellaneous - here's a little story that might help you!
It was my DD's 5th birthday. We booked a night in a premier inn near legoland as a treat. I was pregnant at the time. In the morning we were rushing around to get to the breakfast we'd paid for, but she wouldn't get ready! I was still feeling ridiculously sick, even at 6 months. We were late, and going to miss breakfast.
Normally when she's difficult at getting ready, we'll turn it into a game, or I'll coax her, have fun, fix it that way. But for once, I just wanted her to put her shoes on without a stress. So I said 'FGS why can't you just do as you're told for once'. I never normally shout at all, in any way, so she was shocked. Then cried. I made her cry on her birthday, and it felt shit.
I just wanted her birthday to go perfectly, to have the best birthday memories ever, but missing a big breakfast would have ruined things, cost money and meant we had to eat at legoland (too expensive).
Anyway. Carried a crying birthday girl to the restaurant. Tried to claw back the atmosphere and to not throw up.
Got to LL, and then saw DD just wasn't herself and I felt so crap. So I knelt down and said 'I'm so sorry DD, I didn't mean to shout. I just want you to have a great birthday'.
The smile on her face I won't forget. Utter relief. She hugged me very tight and said 'Thank you mummy. Sorry I didn't put my shoes on'.
Wow. Rest of the day was awesome 
My parents never said sorry. And they did a million times worse.
If something goes wrong at work and I get stressed, I just say, mummy is very stressed so it would be best to give me some time right now. DD is mature enough to take herself off. I think it's important to show you're human, and all emotions are acceptable, just depends on how to handle them. You're teaching them how to handle bad emotions; anger/stress etc
Don't beat yourself up or think you'll be your parents. Everyone makes mistakes. The key is what you do afterwards to fix it, and then not to keep making them.
Good luck all x