Your ex offered to pay his share. Your friends refused. End of story.
It sounds like you have some pent up resentment toward your ex. Let it go.
Sorry, these threads always ask who’s wrong and instead of writing “you’re wrong” I wrote “your friends are wrong.” I type faster than I think.
I think that somewhere in this sordid tale, is one reason why your ex is your ex.
This.
BTW, such problems seldom arise in Thailand. The person with higher wealth or station often pays automatically; if status is similar, it’s an honor to be the one to pay!
(I’ve read that income disparity in U.S.A. now approaches or exceeds that of countries like Thailand! In U.S.A., is it typical for higher-income person to almost always pick up the entire bill?)
This is a fair point. However, on a related note, I personally think it’s all kinds of wrong to invite exes to a double date, which this basically was.
I’m imagining my girlfriend being invited out to a dinner by an acquaintance couple plus her ex boyfriend. No way I’m cool with that. I’d first ask her not to go, then definitely ask to tag along, and probably be pissed about it. I don’t think I’d run up the bill and act the fool, though. I’d likely try to impress the hell out of the whole group to drive home that my new gf traded up, but hey, catch me in the wrong mood and who knows.
This was where it went wrong.
You should have just told him “no”.
If pressed, say “They don’t know new boyfriend at all; they just want to reciprocate for when we entertained them before.”
And you shouldn’t have called the UK friends at all – asking puts real pressure on them to say yes. Should have been handled between you and ex-boyfriend, without them being involved at all.
But as you said they had a nice dinner, and they seem to have paid without any problems, no harm done. It probably bothers you more than them.
I definitely agree with this. I see where the people are coming from who are saying that it is rude for the new boyfriend to have asked to come along, but if a couple who knew my husband called up and said “Hello, we’re in town – is it all right if we have dinner with you and the woman you went out with for five years before you met your wife? We’d like to see you both!”, I’d be cross, too. I don’t know if I would ask to come along, but I would definitely ask my husband not to go and feel very cross at the couple for ignoring me and our marriage and putting my husband in that situation in the first place. So I can completely see where the new boyfriend is coming from, and why he was so grumpy as to run up the bill.
Yes, Randy, we know. In your world, words like “should” or “right” or “wrong” have no meaning. It’s all silly philosophy major bullshit, and nothing matters unless there is a tangible result. Okay, already.
Anyway…
I probably would have done the same.
Ha ha ha. Anything short of making the host rend the cash our of your hand means you’re a freeloading jerkwad!
No, it’s certainly not the custom that the higher income person always picks up the bill because it’s impolite to discuss one’s income. I don’t know the incomes of 95% of my friends. Salaries can vary widely and in the age of easy credit, it’s impossible to know who is really well off and who is just pretending.
As to the OP, I believe the UK friends were a tad rude asking your ex-boyfriend to attend without inquiring about his current dating status. Certainly the OPer could have mentioned that fact when they included him in the invitation. The new boyfriend was boorish for running up the tab and criticizing the restaurant choice. And, finally, the OPer was out-of-line for calling up his ex and chastising him like a naughty schoolboy, when he had done nothing wrong.
No. Your ex offered to pay, the UK friend declined, end of story.
Here is a question for you, where in Miss Manners does it recommend calling out someone for not paying (what you perceive to be) their share of the bill the next day?
So, how many times are you supposed to offer something before you can take “no” to mean “no”? My intuition says once, because I presume people to mean what they say so if they say “no”, most likely they mean “no” and if they meant something else, it’s their fault for not saying that. But I’m socially inept and rude, apparently.
So, is it twice? Three times? Four times (as is the Chinese custom, if various etiquette websites are to be believed)?
If there is a minimum number of times, is there a maximum one? If “no” doesn’t mean “no” the first time, why would we be sure it means “no” the second or third or fourth time?
To those who think one should offer more than once, would you think it rude/blamable if someone insisted beyond a certain number of times? How many?
So many universal etiquette rules, so few people who agree on them.
You’re making a lot of assumtions about a snipet of conversation. It could ahve been preceded by an hour of discussion of the ex. The OP has not made that clear.
I guess this is where I notice distinct differences between the gay and straight world. In the gay world, it’s relatively common for exes to still remain in the circle of friends. In my experience, anyway.
I have a lot of gay friends and I only know of one guy who has no contact with his ex boyfriend.
Don’t misunderstand, my husband’s ex and all my exes* are still in our friend group – I’m quite close with the woman in question, much closer than I am with a lot of friends I’ve known for the same amount of time. I would still be upset if a couple invited her and my husband, and no one else, out to a nice restaurant for dinner.
So in Thailand, I could never offer to pay for dinner and everyone would be happy for the honor to treat me? Sweet! I’m coming to live at your house; you’ll have the honor to pick up the tab. 
This is a cultural difference from Thailand. On my first visit to teacher’s ready room at local school I was surprised to see all teachers’ salaries written on the blackboard. (With more than 3 to 1 ratio between highest and lowest, even ignoring headmaster.)
It’s hard for me to tell if your message is intended to have any serious content, but, yes, Thais do tend to be generous. (But don’t forget the generalization: All generalizations are wrong.)
Had the OPer mentioned the new boyfriend during the initial invitation, the OPer would have known for certain that he was not invited to the dinner and therefore would not have agreed to call the UK hosts back and inquire as to whether he could bring along the new boyfriend.
If it had been me, I would have insisted on leaving the tip.
I would have left a nice tip, making sure ex saw it.
Your story reminds me of the all too common scenario I have experienced many times - mostly in LA.
People would go out to dinner and one (or two) would order the most expensive things on the menu, drink several pricey alcohol drinks, and then be the first to suggest, “Let’s just divide the bill equally…”
As I would normally just eat a salad and have ice tea, I had no qualms whatsoever in saying, “No way!”
I would get dirty looks, but after the dinner, most everyone at the table came up to me privately to say, “Thank you for having the guts to say that!”
Still, if I were to invite people to dinner - no matter how many - then as long as I invited people, it is my obligation to pay for it. Yes, including tip.
So, your ex’s BF was a boorish ass, but he had every right to order what he wanted and the visiting friends should be expected to pick up the bill.
Oh, it happens in other places, too, believe me. It’s usually the people who are slamming down top shelf drinks who will suggest that.
Wait, I’m confused about whether the $200 you mention is half the bill or the whole bill. I ask because if your friends are Londoners, $200 would be a laughably small bill for dinner for five. Right now on xe.com, it’s not even £130. I’ve often spent more than that on dinner for two. I don’t think your English friends will have been that bothered.
(Though in the ex’s situation, I wouldn’t have invited my new boyfriend and I would have insisted on leaving the tip).