Saw my exboyfriend at New Hire day at work...

So, I process badges for our company's new hires and first in line is my ex boyfriend from highschool. History: We co-mingled in highschool with hand holding, kisses and thoughtful gifts, but nothing more. There had always sexual tension between us but we were completely on different levels; I was the school girl, he was the bad boy and it was fun, but I had over protective parents and nothing went beyond that. Until however after highschool, we shared one single night together before my current husband was even in the picture. He was a lot smoother and confident in his adult form and felt great, unfortunately I started my period early so it was a horrible mess and I was appalled. The next day we talked and said he was in a relationship so we didn't persue a relatio ship and after that we never talked again. So now fast forward 9 years, I keep thinking of his last memory of us and it makes me so embarrassed when I see him. He was sweet when I saw him at work but I still can't get over that last and only night we spent together. Can there ever be a normal work relationship or should I completely avoid him altogether? It's a big company to chances are I will hardly ever see him which would be great. He's one of those people who will joke about the whole ordeal and I'm not that confident.