DP worked away Sunday - Thursday and had the day off today so we dropped the two older DC at school then took our two year old and dogs to a country park to play, walk and picnic. When we were having the picnic, he threw a stick that was under his leg and one of our dogs jumped up to fetch it, knocking his drink over in the process. He immediately shouted at and smacked him 
I personally would have laughed if he'd done it to my drink and didn't see the big deal but he was fuming. I was fuming with him as our dog was cowering away from him after that. DD and I were throwing a ball for the dog after lunch and DP called him to return it to him. Our dog returned it to me and sat behind me. DP picked up his ball and put it in his pocket 
This evening 8 yo DD ran out to the sandpit (about 5 paces from the back door) without shoes. DP shouted at her to get back in and get shoes on. DD replied that she always takes her shoes off in the sand so she doesn't bring sand into the house and he issued various threats about removing privileges but didn't actually go out to enforce what he'd asked her to do. She popped back in to go to the toilet ten minutes or so later and he locked the back door and hid the key, telling her she wasn't going back out unless she had shoes on. She did so but only because she wanted to go outside, not because she'd listened to him which isn't him winning as his smug expression showed he thought he had done.
Later on she was playing with something and there was some debate over whether she or her sister had been playing with it first as they were arguing over it. Rather than help them resolve it, he just removed it and put it out of reach - leaving them both in tears. They were later playing with a train track and had been playing nicely for a good half hour but then were beginning to bicker. He went in and said "if you can't play nicely, let's put it away" and broke the track up.
Finally, at bedtime he told 8 yo to sit down so he could brush her teeth. She went to walk past him and he restrained her by the arm saying he'd said it was time to brush teeth so do it now. She said she was going to get a drink of water first and he refused to let her go. She explained that I always say she shouldn't drink just after brushing so she needs to it beforehand but he refused. She then became upset and said she wanted me to do it and he threw her toothbrush on the floor by the toilet so it had to be thrown away.
I don't know if he was tired after working away or had a bad week or something but AIBU to think his behaviour was completely unfair today? He has form for being like this once a week or so but today he just seemed on a complete power trip. He's huffed off to watch tv in bed because I gave DD a new toothbrush to brush with and I'd like some opinions before I approach it with him.