I don't see a problem with hugging goodbye, but yes, perhaps continue to draw boundaries by not touching him otherwise and by not hanging out too much 1:1. I have found with male friends who think there's hope, even when I've said there isn't, that when we continue to hang out 1:1 they get the wrong idea. I wouldn't bring it up to him since he hasn't brought it up again himself, and like you said, it's an uncomfortable and painful conversation. It doesn't seem he has asked to date you again, so I would just continue to make it clear through your actions that you're not interested.