Working with ex

My ex boyfriend was recently hired at my workplace. I do not have much of a problem with this as we have progressed well past any awkward stages and have both been in satisfying and committed relationships for a while now. We are simply friends, if even that at times. However, I am worried about telling my boyfriend as I don't want him to feel uncomfortable or hurt about it. I also don't want to not to tell him because if he were to stop by one day, I imagine he would be very confused and upset. Any advice on how to break it to him best? Please and thank you!

for him not to get worried, casually bring it up once nonchalantly and wait for his reaction.. if he seems worried or upset by it-- be reasonable and tell him, it wasn't your doing that he was hired. and you both are mature individuals who are very happy and contented with each others' relationship. if he is still upset, ask him why? is it because he doesn't trust you? then rebut him by saying that is why you gave him the heads up-- because you are open to him about everything. I am pretty sure though that he is cool about it. ;) good luck! :)