My (22M) school friend (22F) asked me out and I said no but now I regret it!

So there was this girl in my school. We did not talk much in school, but we started talking recently when I wished her happy birthday. We talked for a few months and eventually she asked me out on a date, but I refused because I was emotionally invested in another crush (I did not give this as the reason though). I felt very bad for her while rejecting because even I enjoyed our convos and just rejected because it wasn’t fair to her. She seemed really sad when I said no.

I eventually ended up asking out the other girl, but turns out she was not that into dating at the moment so it did not work put for us.

Now about the first girl, I think that I should have gone out with her because she seemed to be really into me, and was genuinely interested in me. I don’t know what to do.

Am I just lonely and want affection? Or do I genuinely have feelings for the first girl?

I don’t want to ask her out again only to end up hurting her once more.