Seeing my ex at work

So me and my ex been sort of together since high school. We also work at the same place. Since the time we started seeing each other been about almost 3 years. We never put a title on our relationship because both of us are in such a distance colleges so we basically have a rule that when we're together, we're together. Everytime we come home for break like thanks giving, winter break, summer we would come back to each other and when the break over our relationship would put on hold. I know that I was madly in love with him and I couldn't handle the way out relationship was going so this winter break I gave him an ultimatum and he said that he doesn't want a relationship so I told him I was done. I was complete shattered. Two months without talking to him just been so hard and different since we used to talk every day for 3 years. 2 days ago he texted me that's he's coming back for spring break and he can't wait to see me at work. He acted like nothing happen. I don't know what to do I made a decision to get over him but I know for sure when I see him again I couldn't resist him.