It sounds like you may have jumped into being his friend a bit quickly. Being friends with an ex can be hard, even when you no longer have feelings for them. Perhaps a more loving thing to do for yourself would be to pull back from trying to be his friend and let yourself heal and grieve. (You certainly want to be friendly, if you run into one another, but you don’t have to hang out) Give yourself the gift of allowing time to get over the feelings of loss and possibly even move onto someone who is a better match for you.