Do you have any close female relatives you can talk to first? An aunt, cousin, sister, or something? How about a friend's mom or older sister? If you talk to this person first, you can ask them to come with you when you talk to your parents.
I think once the shock wears off they will be ok. While they may be very disappointed in this turn of events, they're still your parents and I'm sure they will still love you and want to help you. Once the dust settles, you'll see they will come around.
You will have to tell them at some point. Which parent is easiest to talk to, your mom or your dad? Maybe you should tell the one that's easiest to talk to first.