girlfriend? one time thing? what do I doooooo

It's kind of a long story and i'd like to keep this as short as possible, but recently I kissed one of my old friends. We've known each other since preschool and our families are close, but we've had an iffy relationship over the years. 

We were listening to music in my room and making kandi while I was opening up about how I feel pretty undesirable and how no one will ever feel *that* way about me, and they said that they did. like, out of nowhere. (keep in mind that this person had multiple people that they COULD have been with instead, and they were flirting with this other person like a few hours before)

So I asked if we were both getting the same signals and I just.. leaned in.

The next day we went thrifting with a few of our friends and on the drive back they put their head on my shoulder and we watched the street lights. But after hanging out at my house for a while they had to leave and I asked if they wanted to go upstairs to grab their jacket (with the intention of maybe quickly kissing them before they left) but they pulled away when I reached out my hand and clearly wanted to stay downstairs.

What do I do? I'd never want to force myself onto someone and I need to make sure we're both getting the same signals and they don't secretly hate me.