Honesty is the best policy even when it's hard. Keep it simple and make sure to give them time to understand. It'll be hard on your parents at first. If it'd make you feel more comfortable have someone you've told be there with you. Go in non confrontational and just lay it on the table. If you are worried about them pushing you to do something you don't want to do have a list of what you see as options. If you are leaning one specific direction have your reasons ready. It's your choice in the end what you do. If you need to talk feel free.

-Tig