im scared to tell my parents!

[Prairie Pirate]

Do not, I repeat, do NOT tell them in a note.

It sounds like your parents are pretty good, so try not to stress too much (easier said than done). Take a few days, or a week, or whatever, and figure out exactly what you want to say to them. Think about the big questions they're likely to ask. It's still nerve-wracking, but things like this seem to go easier when you're prepared.

And unless you want to be like me and end up stressing for months waiting for the right time, I'd recommend setting a day to do it, and stick to that deadline. Drawing it out makes it worse.

Good luck!  

[Chefeetaboopers]

Be honest. Tell them how you feel. I'm quite sure they'll accept your sexuality!  

[GreyJedi]

I'm sure your parents will love you. I have a gay daughter, and I don't love her any less than my other children.  

[Rikku Takarai]

I know everyone else has already said this, but...
I think it's best to just force yourself to do it. Of course when you're ready, just be sure not to back out. And if it's hard to just come out and say it, just do something stupid, or mumble something so they question it. (It's what I do when I'm trying to force myself to say something. It makes it easier to admit some things-- for me at least.)
People all have different ways to spit something out, but the sooner you do, the better.
Besides, it's best if you tell them aside from them just finding out. Being honest can show that you trust them and can be completely trustworthy... and that you're brave enough to come up with the truth no matter how hard it may be. And by holding it back longer, it may hurt them a bit more. Like a, "Why couldn't she just tell me? Doesn't she trust me?" kinda thing.
If your parents love and care for you, they'll accept it.