Seems to me you still don't have feelings for him (your last paragraph), so this is just an ego-thing for you. You want to believe he has feelings for you and that you didn't spread your legs 'for nothing'.
If he did have feelings, he doesn't now. He told you he is interested in someone else. I'd be avoiding you too, if I were him.
It sounds like you had a nice, romantic night with good sex. Stop psyching yourself trying to make it more than what it was. Get over yourself already. Geeze.
Second thoughts can generally be amended with judicious action; injudicious actions can seldom be recovered with second thoughts.
--Cyteen by C.J.Cherryh