I had the same situation with a friend before, we both were there for each other when one of us had a broken heart. You just let them know they deserve more (something my guy friend did many times for me) and just go out together and have some fun. Stress relief. Be there when he has nobody to hang out with. No dinner and a movie dates, but just going and doing something together that will cheer you up is so fun. Luckily, I was the one that broke it off, so I didn't have weird feelings, but sometimes it was heard for my friend to get over it. Now he is getting married and I have a long term relationship so all is well. If you truly are good friends then it won't be awkward at all.

On the other hand, there are those people that say they are friends with their exes but really just can't handle it. I trust that you aren't that type since he has already dated since your relationship.