I'm a single parent.
Never felt MORE single than the one time I took my then 3yo to an AI holiday.
Thought it would be easy. Reality was kid was clingy and literally wouldn't be put down for the first two days (big and heavy in the heat!)
I had to carry him and a rucksack while dragging the suitcase to find the room in the first place (3*, not the sort of place with bell hops or whatever helpful people with trolleys you might get in a fancier place).
At the buffet on the first night, he refused to be put down again because it was overwhelming so I had to carry him and try to hold a plate and get his food on it one-handed. Eventually managed this, thought I was winning, put his plate down on our table, went back to repeat one-handed process for MY food.
To return to the table and see the first plate had been cleared away, because obviously nobody leaves a lone plate unattended so it must be finished with despite being full.
Honestly I almost cried.
I'm sure there WERE other single parents in the world but at that time in that restaurant it really didn't feel like it.
Of course it got better, I worked out to take a spare item of clothing to "bagsy" a table, by day two he let me put him down, by day three he would stay at the table by himself as long as he could see me at the buffet etc.
But what there wasn't was a kindly army of ex-pat grandmothers waiting to offer to help me like some people on here have suggested.
I think OP will have a tough time no matter what, and I'd assume a VERY hungover arsehole incoming in the early hours. Realistically I expect she'll stay and he'll make it hell for her but the logistics of leaving solo will be too much.