I assumed there were head phones in the DVD.
So, to sum up, just so I know i've got this right...
you were on holiday with friends, but staying in seperate flats
You had a meal out one night and your son gagged and vomited at the table when you were out.
You friends DH was not helpful when you son injured him self requiring stitches.
you went back to theirs in a spotaneous way to eat your seperatly bought take aways.
you took your sons DVD player with you to occupy him while you ate, as he doesn't eat.
Said friends DH turned it off and made him sit at the table.
Your Issue is
That the DH is overbearing, rude and unkind to you in general
That he igored you in your hour of need, with the head wound
That he touched you boy without asking, and he made him do somehting you were not going to do...
Well, to me, it seems like it was a relaxed thing, with the take outs, unplanned and in thie circumstances only, I would say its not really that big a deal that he didn't sit up and eat with you initially. So, what would he do if he hadn't had the DVD player? Seems fair enough to me tat he be occupied...
So, I do think the man should have at the least asked you first. NOt picked him up without talking to you. so YANBU on that point.
Secondly though, It really is NOT te doe thing, usually, eating issue or not, to let children opt out of meal times, let alond opt out and watch a film. THat really is just rude. Unless, perhaps, you are at home with friends and he is in another room...
Its probably more important that he sits up at the table, so it normalises eating for him. Its past the point of being a 'little' problem that your HV can advice and help you on. He's 5 now, he needs to see a specialist on eating peadiatric eating disorders. There is a psychological reason for him gagging with food. I presume he's no physiological reason? So, he needs councelling. YOu need to address this sooner than later. What happens at school?
The more he sits up and watched people eating normally, the more he will see that that is actually what you do. He will learn from it. YOur GP can refer you. They have specialist units at most large hospitals, otherwise they'll refer you to nearest place with a center.
Good luck with it. I hope he gets some help for it soon.