rise_up, good for you for standing up for yourself.

I know that was very difficult for you, and I hope that you know that it was not selfish or cold-hearted to put your own needs first. I've told you before how brave I think you've been through this, and that's bringing you a lot of strength.
Your e-mail is good; it does recognize that this is probably hard for your parents (Support and empathy), but you also explain what's in your best interest and offer an alternative (truth). Even if you disagree with them, you're more likely to get a better response if you show that you're willing to look at things from their point of view.