He's behaved appallingly on several levels OP, but you already know that. For what it's worth, here's what I would do.
When he gets home, be ready for him. He sits down with a pad and a pen that you will have placed on the table, and he lists everything the holiday has cost. The cost of the holiday itself, the hotel, golf, transport etc, and then all the incidentals - meals and drinks out, itemised day by day, any bets they had among themselves, etc. Absolutely everything. Make it quite clear he has one chance to get this right and make a full disclosure, and you will be checking it against his credit card bills, bank statements and social media account. Take screen shots in advance so he can't delete the evidence. Total it up and write the resulting figure on a fresh piece of paper in big and place it on the table between you.
Then you will have a very full and frank discussion about the current state of your family finances and how he can justify spending that amount of your joint money on a selfish jolly just for himself. Ask him what all the admirers of his FB posts would think of him if you revealed to them that he expected his wife to work two jobs to pay for him to go on that holiday. If you can't afford a family holiday, let alone a similar break for yourself, then I'd lay that on with a trowel. Ask him on what basis he expects you to be the Cinderella in this relationship and tell him that is not happening going forward.
I'd also address the issue of him lying to you, and ask on what basis you can believe anything that comes out of his mouth going forward. How does he envisage any marriage working on that basis?
Given that he's also been playing fast and loose re the Covid risk, I'd be asking him which of you and the DC he is most willing to risk catching the virus, since he's obviously not very bothered about it. What's his preferred pecking order there?
I'd be asking him how he is going to repay that money into the family pot, because he'd better have a plan. Perhaps he has some assets he could sell- a set of golf clubs, and possibly a bike? He sounds like the sort of selfish so and so who'd own one of those too.
Make it absolutely clear you are serious about all this, because your one mistake throughout has been to agree to him going for the sake of a quiet life. Make it crystal clear you are serious now, because if you don't you are just teaching him he can get away with this sort of stunt. Time to make a stand I am afraid.
Once trust in a relationship is damaged, it is very difficult to get it back again. I am appalled on your behalf. ☹️
Good luck.