Okay...help? Plz...

Basics:
1. I love a guy and have done so for three and a half years, but he has a gf.
2. I have known another guy for about a year and at least we talk. But he loves another girl (he is not with at the min).
3. This guy and I are kinda, sorta going out for a coffee tomorrow (*Im in shock*lol) we both kinda asked each other. I dont know how I feel about him (or vice versa) and Iv never done this before.

Heres the prob (incase u have not noticed lol)...I think I might be trying to move on from the guy I love and I dont know if the guy im going to the cafe with is doing the same (trying to get over the girl). It cant hurt right? Two friends and if it goes further then thats good...it may not get us over the people we love but at least we can have a good time right?
So what am I asking? I have not got a clue. Advice on how to act tomorrow at the cafe I guess. Got any? I have no plans of flinging myself into anything serious but...

just play off of how he acts if his intentions were to go further you should be able to figure it out just act normal nice friendly like you always would unless you want it to go further then tell him something lovey dovey