Not ready for a relationship

I just started my new job last week and one of my co workers is very cute. We always joke around and have fun while we are at work ..we recently added eachother on Instagram and started talkin a little more through Dm ..he asked what were his chances with me I told him about 60% mostly because I don't think I'm ready ..for more than one reason..he sent another message after that & said "so I can't have a chance right" idk how to respond back because he's a real nice respectable guy he also has a nice body ..I mean he's perfect (so far) I think I'm scared to fall in love again I know that I want my next relationship to be my last also don't want to get hurt ..and deep deep deeeeeepppp down inside I think my heart belongs to someone already ..I don't want to get into anything with all this in/on my mind ..I guess I'm asking how am I suppose to respond to his message ..& should I just let things take it's own corse ? #everygirlwantsafairytaleending