You know, data privacy is a big concern these days. And yes, posting these without permissions from the person is considered "revenge porn". Regardless if you had any intention of blackmailing the person, getting back at her for something, or not, this can be a punishable offense.
Just take a look at this:
https://en.wikipedia.org/wiki/Revenge_porn
I don't think you should be angry and bash the people who pointed it out. Rather, take it as a kind reminder in good faith. Besides, you may no longer be a part of this person's life, or she yours, but consider for a moment what she would think should she find out, or ever worse, have an unpleasant encounter with someone else besides the two of you who somehow got a copy of the material.
I understand you probably didn't consider all this when you, probably completely innocently, decided to post this, but anything with ex- in its title should be a major privacy red flag.
Edit: Now I know this entire discussion got off the rails real hard, and especially some people in it try to make you look like the worst offender in the history of the human race, but far from it, this thing with the postage of personal pictures happens all the time. You are not the first, and probably not the last. The idea of my post wasn't to bash you, just to add a few cents from a perspective that I don't think the people in this thread have considered to comment.
Thanks for sharing all of them here. 
