He has a girlfriend

So I think I'm falling in love with this really good friend of mine, but he has a girlfriend... What do I do? I think he might like me too but I'm not sure. We're at the same school so we always lunch together with a couple of friends and we're always hanging around together during the breaks. We're not having school next week so he's going to come over to my house to hang out together... I'm really trying to prevent myself of falling for him but I don't know how long I still can... Please help.