Why would an cheating ex wish you a happy birthday through an unfriended Facebook?

Anonymous
I had an ex that blamed me for cheating when he was the whole relationship. He has always wished me a happy birthday the first time we broke up in high school. We got back together in college because he wanted a second chance. He deleted my happy birthday babe post on his wall and unfriended me. That was it and I turned off my phone. Its been months since then and I've been happy and dating. He doesn't know that I found out he was cheating with his coworker. So why is he messaging me through the same Facebook that he unfriended me from? I have never responded and never will.
Why would an cheating ex wish you a happy birthday through an unfriended Facebook?
2 Opinion