Wow what a difficult post to reply to! Please excuse my poor sentence structure...
The motto I have always lived by is "Nothing ventured, nothing gained." I recently went though the same situation that the OP went though. The topic of joining the military is a sensitive one with my family. Risking my financial support in getting my PPL and finishing college, I let my parents know though several stern emails exactly what my intentions were, and that I know what the risk are.
I explained to my parents that the driving force behind my reasoning was that I wanted to repay all those people for putting themselves on the line for a person that they have never met and that I knew that I would never be able forgive myself if I never tried to get that NFO or Pilot slot, let alone joining the military.
Last week however, my parents sent me an email saying how proud they were of me for following my desire to fly and that they fully supported my wishes to try to join the military.
So what kind of advice could some college kid who hasn't even finished his application packet give to anybody that's currently going though the messy process of explaining to their parents on why they want to join the military?
1. This one is a given... Know that your parents love and care for you, for this reason they will try to protect in whatever way they can, even if it means screaming at and lying to you. However, if you hold your ground they will respect you for it in the end.
2. The question of "what if" is one of the worst things that you can put yourself though. Trying and failing is always better that not trying at all... except when it comes to skydiving and hand grenades.
3. You are a grown human being capable of rational thought and making sound decisions. Whatever power your parents had over you disappeared when you turned 18. Use a bit of that brain power and realize that it's your life to live.
*HAH, I did not realize that this post was from 5 years ago, sorry for resurrecting the dead.