Dear Roberta, aged 7 or so (as you won't be called Robby for many years to come):
First of all, I want to assuage your fears -- there will be some bumps in the road ahead, but no matter what life throws at you, you will always find a reservoir of strength in some way or another to get you through. So don't find this letter as cause for alarm--you will be okay.
The thing is this: your parents aren't perfect and aren't necessarily going to know everything about how to raise you correctly. This is because they, themselves, had parents that didn't know everything about how to raise them correctly. They are also too afraid to admit this to themselves and to you. As a kid, you really have no choice but to follow their lead. Don't worry about this--their reign over you is a finite span of time. After this, you will be able to make your own choices and determine the paths you take in life.
It's not all rainbows and butterflies, though. You will experience the loss of people very close to you and deal with it in unhealthy ways. Again, don't worry--you do not become a drug addict, a college drop-out, or give in to the despair. You find a way through it. It might be messy and imperfect, but the chutzpah and resourcefulness you have will get you through it.
I wish I could go back in time and guide you through what's going to happen to you over the next couple of years, but the only reason I am who I am right now is because of all that happens -- good and bad. So for now, I can just hold you in my heart a little while and feel compassion that you will have to go it alone for the most part.
I'm still cleaning up the aftermath of all that, but I'm doing this for you and me. I'm doing this for us. I'm doing this because you deserved to be taken care of better. You deserved to have someone notice how much pain you were in and how much grief you were hiding. You deserved to have proper meals, and more family activities that didn't involve the warmth of a television. You deserved to have parents who loved you and the body they created. You deserved to have parents who could place your needs over their insecurities. It might be a little late, but you know this now.
It's 10:30 and past your bedtime, and approaching mine. But if you could reach out into the future and send me some of your dreams, I'll try my best to live them.