Ok, you're still seething. Hang on another 24 hrs before deciding what to say to him. If he's flaunting, he's expecting a bun fight. That's not what you want, you want him to hear and respect you. So ignore the flaunting. If he can't get a rise out of you by playing games, you're on a more mature playing field.
It's like my H flaunting how busy he was this weekend but hiding what he was doing. He was testing me. I didn't rise to the bait.
But you do have every right to feel hurt. It's hurtful. It's rude and immature. And so soon after coming home. But you must show him you're not going to have a tantrum, but you are also not going to accept secrets. Tomorrow you can calmly but firmly remind him of your agreement and that you fully expect him to keep it up. If he doesn't, you will look into _________ whatever it is.
You have time to decide what the boundary will be. What will it be?
Look at it like how you would handle a child - keep those boundaries firm without showing he got to you.
You can do it! Maybe initially you should write out here what you are going to say to him so we can support you.