The two of you are friends, you shouldn't completely avoid him. You can't do anything to get him to not like you, but chances are that he will eventually get over you and move on. Especially if you only treat him like a friend. Only hang out with him when you're with a group of friends if you're too worried, but it's really not worth it to just quit being friends.
If he asks you out or tries anything, then you need to tell him you're only interested in being friends. Otherwise, you don't need to talk to him about it. And chances are, he'll only try anything if the two of you are alone
With the play, just go on as you normally would and forget about him liking you.
Hopefully this is at least a bit helpful!
