clay5 - If you definitely think he is a good guy who is not going to turn into an a***hole over this, then I would recommend being really honest with him i.e. saying, "I really like you as a friend and a person. I am really sorry because the past couple of weeks I know my behaviour has been giving you the wrong signals. I do mean it when I say I don't want a boyfriend and don't like sex. Last night has made me realise that things have gone too far due to my behaviour (hugs and kisses) giving you the wrong messages, but I really really mean it when I say I just want to be friends. For the next few months, I think we should only meet in public and not hug or kiss at all. Otherwise, I think one or both of us will get really really badly hurt."
I think it's possible even for ex partners where one dumped the other to remain friends. However, sexual attraction is a powerful thing. He's attracted to you and you've previously given in (understandably) to liking having cuddles from him, etc, hence the need for cast-iron boundaries around the interactions between you two at this point in time so neither of you gets more hurt by the situation in the future.
Probably_Drunk - The guy may be a wreck for a while. Many people are a wreck after being dumped or finding out that what they thought was a blossoming relationship isn't. Hopefully, he'll then realise that 2 weeks of cuddling and kissing is a pretty flimsy basis for planning the rest of his life around. Many relationships don't work out and many last a lot longer than 2 weeks before breaking down. If clay5 follows through on her intention of honourably stopping all romantic / sexual interaction from now onwards and the guy goes permanently off the rails, I would guess there was something majorly wrong in his life prior to him developing a crush on clay5 and trying to become her boyfriend. People get dumped for all sorts of reasons. It's horrible. Depending on other factors (like their overall mental health, what else has happened in their life, etc) they get over it more or less badly, taking a shorter or longer period of time to accept having been dumped. It seems to me completely unfair to paint clay5 as potentially ruining this guy's life. Surely anybody who lets a two-week romance ruin their life must have had other problems in that life to start with (otherwise, no matter how intense the 2 weeks were, they can afterwards focus on the other good areas of their life until such time as they're able to dismiss it as 'those crazy 2 weeks [e.g. those crazy 2 weeks I thought I would marry clay5 despite her being a committed lifelong singleton]').