I really appreciate everything I've been seeing on this site. I am learning alot about how to deal with the pain that tends to come from these type of relationships, so thank you everyone

Was hoping someone could help to explain the social media thing after a bit of quick back story.
I recently pulled out of a situation with someone who has very strong BPD traits. We had a very close relationship artistically, and were very good friends and alot of signals crossed between us romantically - but when I finally let her know my feelings, she pushed me away and said she couldn't bring herself to make the romantic connection (which apparently confused her because she felt we were like 'soulmates, and that I was "the total package'. I believed her reason to be fear (which she stated a huge part of it was), and although the possibility exists that she may not attracted, I believe that making herself vulnerable to this dynamic was the problem.
In anycase, to avoid the emotional pain and confusion of our relationship, I had to cut contact with her for my own preservation. The situation hurt too much. Scenarios would invade my mind constantly and replay themselves, trying to make sense out of a situation that in essence, made no sense... .it was emotionally exhausting and very harmful.
She was very hurt and didn't want to break the contact at all (for the extreme 'emotional connection' she said she felt and the fact that we have a long history of artistic expression between us)
- but I made it clear that I had to.
And now, late to this particular game... .I'm aware that social media is a big trigger... .unfortunately I fell into the trap of not blocking it out completely.
After a few weeks of being out of touch, the old computer comes out and I see she has posted a recent picture of her and her ex, together. The picture in every way (including the caption and the funny posing) emulates the type of photos she and I would take... .it is very much for me to see (I don't simply believe that this pic is a coincidence) -this feels far more like a prop - and the look on her face is kicker, like she swallowed a bag of rotten bananas... .they were HORRIBLY unhappy together.
Can someone take a shot at the reasoning behind these outbursts? Punishment? charming? Emotional blackmail?
In all actuality I don't believe she has rekindled that relationship (or if she has, she knows it's serves as a quick band aid and a ruse) -it feels more like something you'd see in a dept. store window, if that makes any sense, like she's posing (there's no substance behind any of it). But she knows that relationship was a sore spot for me (it got me to engage her emotionally in the past) and seeing it still stings.
I really appreciate the insights here. I've dated people who have these traits before, so I am also doing alot of self reflection as I read up here... .every little bit helps and thought would be appreciated!