There are a lot of good advice here so far - and I would agree that counseling and finding ways to move forward is key.
Although I have not experienced what you have with the GT issues as a child, I have had challenges due to late diagnosis of a disability that did impact a significant part of my childhood (to the point that whether I had any GT services or not was trivial in comparison to the challenges I had to deal with).
What aeh and polarbear have said are what for me were keys to moving forward when I was your age... understanding that the past does not have to define you, and also understanding that our parents' own experiences (and to some extent, the world around them at that time) will have shaped their perspectives on raising their children as best they could see, fairly or unfairly. Ultimately, although the past may have impacted your life, as polarbear has said, it does not have to define who you are or who your DD will be.
It is easy to spend time on "what-ifs" - I certainly had dwelled on a lot of "what if" as a child and early adulthood. I did not experience the anger you show towards your parents, but I used to wonder how different things could have been with all these 'what-ifs'. However, I do understand my parents' perspective a lot more now, especially having my own children and I understand the choices they made regarding how they dealt with my education and development. When I was younger, it felt like my disability defined who I was - but with time and perspective, it is just a part of who I am but not the central focus of my identity. It is certainly not the defining characteristic of who I am to my children.
IQ will only be one aspect of what makes who you are today and moving forward - it won't be the reason you rise or fall, although it will provide you a tool you can use to move on (or not). You can decide how much you let the past consume you and how you can move forward.
