Simple mention you are a divorcee. Don't make a big deal out of it. With the current high divorce rate it not uncommon. Don't let him find out from a third party. I generally oppose discussing prior relationships with current significant others as it usually only leads to arguments. My exceptions are divorce, children breeded with ex's and prior personal health issues.
According to me, you should confess to that guy about your broken marriage. If you plan on starting a new move in your life with him, then you should definitely tell him each and everything about your previous relationship throwing away all the barriers of shame and insecurities.
Lying about your marriage and pretending in front of him that you had never been married is not a good option. I know it takes more courage to reveal the harsh truth of an iffy relationship with the most important person of your life.
The rest depends on that guy. If that guy really cares for you and has special feelings in his heart, he will definitely accept you no matter whatever your past was.