How to not be homesick?

2 weeks from today I am going to Cape Cod with my cousin(same age as me) for 2 weeks to visit family. I went a couple years ago when I was younger and go homesick and went home early. I'm afraid this will happen again. It's 2 weeks away and I'm already getting homesick even though I didn't even leave yet. I want to go so bad but I don't want to cry or complain when I'm there. I can't bring pictures of my parents and if I talk to them I think about them which makes me homesick. How can I prevent this feeling?