YANBU! I got something a bit similar - Dsis and SIL having a competitive moan (in front of me) about night wakings with toddlers. My DD is 16 so is like Rip Van Winkle (now).
They patronisingly then said to me "Sure DD never woke, she always slept through" and I lost it and said quite sharply "She woke at least once a night for the first two years of her life, when I was a single parent and did every single night waking while holding down a full time job after only 4 month's maternity leave." They have never moaned in front of me since. (each, at the time, had a supportive husband doing half of everything - and SiL has not worked full time since their first was born)
I suggest that the next time they moan you look mistily in to the distance and say "Oh, to be earning €50K as a family - we can only dream of that, we're only on half that amount and will never have a big increase. Isn't your salary due to go up tenfold soon? Aren't you lucky to own a house outright with no mortgage/lucky that only one of you has to work, we'll never be in that position" .
And if they EVER ask you to bring all the wine again, just say "No, you invited us, and if we pay for it, DD/DS will have no lunch money next week. Why are you having a dinner party if you can't afford it." (OK that's a bit pissy, I know!).
Frankly, they sound a bit entitled and moany and would drive me NUTS. I find with people like this you have to be quite direct (I've another friend married to someone earning half a mill a year, who was quite fond of pointing out how I should buy an investment property
. I took her aside & told her it wasn't a runner and would she please not go on about it, and she copped on and stopped talking about it in company.