I can hazzard a guess,he's getting dolled up for a good night out on the town and not worring about how your feeling!
But you,and sitting wondering what is he thinking,is he sad, does he miss me?
All these questions are just making you feel worse.
Get busy planning your night,and put a ban on talk of him and what he is doing,its not your problem,nor really your business now... hes single and so are you.
Enjoy your life!
Stop wasting time worriyng over something that is done and dusted,and you have no control over.