I just want to be friend with him

There's this guy in my class, when I met him I knew we could get along very well. He's really funny and nice and I'm sure I would love to spend time with him.

However one night we were pretty drunk and we kissed. I was hoping he would see it just as smth which doesn't mean anything...

Because that's how I see it, I know it was a mistake because I don't want him as a boyfriend.

Anyway now he has a crush on me and I really don't know how to tell him I don't want to be with him but I also don't want to lose him as a friend.

Any tips?