Bonyk, you have my sympathies. I can't stand people like this.
However, in your case, my ire would be directed at myself for putting up with a pattern of behavior.
What is funny to me is that I just went to a purse party while getting over the flu. I'm not contagious, but still a bit weak and coughing a lot. I took a bunch of cough suppresants and plastered a smile on my face for two hours because I promised I would be there. If I'd had a fever or such, she'd have understood. But I gave my word. I was miserable but fortunately it didn't show. My hub's favorite expression is 'suck it up, buttercup'.
We're friends with a large group of friends/family. Nice, fun people - for the most part. One of the couples is a matched pair of snowflakes. Three (3) times they flaked out on us. The last time dinner was on the table and we were waiting for them to show up when I got a text (TEXT?! Really?) that said 'Sorry, we can't make it.'
The next morning we saw them and my daugther said to their 7 yo daughter 'Sorry you guys couldn't make it last nite,' to which she looked confused and said, 'We went to the street fair last night.' I mentioned it to the hubs and we both looked at each other, smiled and said 'Never again.'
Now we will invite them over if we are having their enormous family/friends group over (because with that many people - who cares if they flake?) but we'll never have a smaller intimate dinner with them. Ever.
They showed, by their pattern of behavior, that they are a bunch of flakes. If I invited them over again I'd have no one to blame but myself for them flaking out. Some of their other family members are a bit flaky but no where near as bad as these two.
I always dial back on a burgeoning friendship when someone starts showing a pattern of flakiness, entitlement, selfishness, etc. So I can honestly say I don't have to deal with this with any of my close friends on a regular basis.