So, what this woman is essentially saying is "You shouldn't be allowed to post photos of an event on Facebook unless everyone who might be able to see them was invited to the event."
First of all: "No."
Second: If someone on my FB friend list complained that they weren't invited to an event and said that they were offended at seeing photos of of the event on my FB page, I would be very quick to correct the situation. They would no longer be able to see the photos because I would unfriend and block them.
While Toots is right in saying that FB sort of "outs" many of our little white lies, that is the problem of using Facebook. You can't say, "I want to sign up for a service to see about everything my friends are doing ... wait a sec, they shouldn't be telling me about *that*! I'm so deeply hurt!"
The writer was not talking about an event to which she should have, by rights, been invited (say, she was the only one of a small group of friends not invited on an outing which she would have enjoyed). She was complaining about not being invited to the wedding of someone whose mother she apparently despises. There is no reason really to maintain a "white lie" here - she had no specific reason to expect an invitation, and should not be offended that she was not given one. If she knows they are married, it should sink in that there was a wedding to which she was not invited. Does she expect that the HC will continue the fiction around her that they are still cohabiting, and explain to her those rings on the woman's right hand are just dinner rings?
MrTango has the right approach - if your "friend" cannot bear to see or hear of events to which s/he was not invited, she should be spared any possible further pain by being cut off (in the Facebook sense, at least).