What does he mean by this comment?

So I ended my involvement with a guy 3 years ago and never really thought too much about him again on account he was a real asshole.As time wore on I forgave him and myself for what happened between us but left it alone. I recently became facebook friends with one of his best friends and the guy's pic popped up on the "people you may know" section. I was kind of taken aback but decided to see if he'd respond to my request. If he didn't,no big deal. But he did! And he posted on my wall with just "Wow...." And that was it. Yet we're still friends on FB. I don't get it...can someone help me out?