I have a crush on a 12 year-old...?

Who is my brother's friend, a son of my mom's friend. His mom is visiting mine from Boston. I'm 18 and a guy. This is the first time I fell (hard) for a young kid. I even get heartaches when I think that he'll leave in a few days. I feel like a pedophile and I know it's unhealthy but the guy is just really nice. He rested his head on my laps, on my shoulder; he teases me a lot and he pokes me all the time. He seems to look for me once in a while even when he's with my brother. Last night, he even said "Be my soulmate." Is this okay/normal/etc.? Will this go away? Also, please give me any advice I need. Thank you.