How do you say goodbye to somebody who has been your Muse for something like three years?

I became friends with this guy at work about 3 years ago and I have always felt this connection with him. I really look up to him and respect him and there’ve been so many times that I have looked to him and how he deals with things as an example of how I should handle things. And I found out today that he’s leaving in about 10 days and I just feel like there is going to be this hole in my life. I really I’m at a loss about how to make peace with this news.