I feel like such a shallow asshole but I can’t take him seriously

I started “talking” to this guy I know since were nine. we been friends on fb for years but I haven’t seen him in person since we were 10.

So after talking daily for a almost two months he told me he was going to be in town visiting his parents and would love to take me out. I said yes i would love too, I was excited got a new dress and everything. Then the day comes we meet up and I hear his voice😵he literally still sounds like a kid his voice is higher pitched then mine and I just can’t talk him seriously I fe like a huge dick but I just can’t get over it. I really don’t want to hurt his feelings he so nice, how can I let him down nicely?