I’m falling for my friend but I have a boyfriend

I’m in highschool and I have a boyfriend we have been dating for about 2 months. He’s as sweet as can be but I’ve been doubting our compatibility for the longest. Last night I went to my friends birthday party and my guy friend (gonna call him O) was there. He kept hugging me and kissing my forehead and I playfully licked his neck. He’s a naturally flirty guy and so am I so that’s how we act with each other. He knows I have a boyfriend but he even hit my butt and I didn’t even mind it. It didn’t feel wrong only later did I realize that it was out of line. We’ve known each other for almost 3 years now and we used to be super close. He said we vibed but I’m pretty sure he meant in a platonic way, so I’m not sure if he is even in to me. I don’t know what to do. Am I a horrible person?