I once wondered aloud to my husband about if I hadn't slept with him and if he'd been my friend instead. He replied "I had enough friends. I wanted a girlfriend". In short, if I'd wanted friendship, I wouldn't have gotten a look-in.
Another thing to consider - just say you find a guy who's happy to be friends. You may fall in love with him - but in the meantime, he might go and find himself a girlfriend.
Never regret anything that has happened in your life. It cannot be changed, forgotten or undone. So, take it as a lesson learned and move on.