People always have mixed feelings about this subject, but i'm a firm believer that you can be friends with an ex. I'm friends with all of mine, yes it was awkward but we got through it and became really great friends.
Try not to push a friendship at first, don't think that you two have to talk, that you two have to be around each other cause the space will do both of you the world of good. Take it slowly, take some time out from each other and see how that goes. You two are the exact same people that got on before, and when you were both dating. Be the same person you were then. Talk about things you two would always talk about, things that interest you both. Treat him the way you would treat any friend.
I know how you're feeling but try not to get caught up in forcing a friendship, if you two are going to be friends then it'll take some time for the awkwardness to go away, but if you're meant to be friends, you will be. It just takes time, that's all.