How do I say goodbye?

Where do I begin to say goodbye? How do I go without saying goodbye and leaving them to think I am coming back in 2 months. It's hitting me like a ton of bricks now that I have just over a week left with my family, I know it's not forever but I also know that if I tell them before I go it will crush them. I am still stuck and would love someone to just give me an opinion. ughhh why is it so complicated?