What is a good way to decribe an episode of hypomania to a friend?

It's best to be honest or he will know you are just making excuses. If you are bipolar just say so. Most people know what that is and there isn't as much stigma attached. The mania part of it involves you thinking you are some kind of god so your actions proly pushed him away. Just let him know you were completely misinterpreting the world around you and that it is a temporary thing you are working on.