I need help with relationship problem quick!!! Please answer!?

So, yesterday a guy friend who hangs out in the same five-person group I do (I've moved away but they all miss me so we're getting together on Saturday) asked me out. I had sort of liked him and I couldn't say no so in a spontaneous moment I said yes (he asked over FaceBook, by the way...) and then we texted and he is way more excited than me, but today as I was practicing theatre for long hours I thought about it in my free moments and I don't know if I want to be in this relationship. I've been out ALL day with theatre, guitar and then I went and wrote to calm myself down so I haven't been on my phone much. I've had NINE messages from him already, and then on facebook there are nine more!!! The nine on facebook go like:

Him: Hi

Him: How are you?

Him: Are you enjoying the rain?

Him: It seems like you would

Him: I love you xP <3

Him: :)

Him: You could probably text me :P

Him: Or just ignore me....

Him: xP

And then I just got a tenth text from him - haven't opened it up yet, not sure if I want to right now. I mean, I'm ONLY SIXTEEN. We've been 'together' for ONE DAY and he says 'I love you'??!!!!? It's really unattractive and it's turning me off majorly. I feel like this is going to be a miserable experience, and I just want to be free and away from it already and it's been a mere 24 hours!!!

BUT I can't break up with him! He's one of the friends in my tightly knit group and we're all getting together on Saturday! What should I do?????