I'm hesitant to tell you what to change in case I make it worse - I'm not an especially talented English student so I feel like it would be best left to someone of higher caliber.
Buuuuuut
My childhood was the happiest period of my life. It was very safe and secure and this was only made possible by you and Pa. I want to thank you for realising how hard it would have been for me to be accepted by the “white” community, because of the discriminatory laws enforced by the government during Apartheid. However, my initial identity was formed in an idealistic, yet insular world that had no relevance to the reality of that political time. Also, you protected me from my own identity by sending me to an all-white school and not accepting all aspects of my identity.
I've just chosen this segment at random to iterate my point.
In this portion of writing you have established:
a) Security with her white family
b) There were discriminatory laws.
c) Idealistic identity was formed, contravening political ideologies
d) Confusing sentence, but - Sandra's identity was somehow held back by the school and her parents not accepting her etc
So you have established those things, yeah? All can be said to be truthful and did occur in the movie, yes.
However, for one, it seems a little bit out of character for Sandra to be establishing all these things in a letter to her Mum. It lacks a realistic feel and it sounds more like you're trying to set up the foundations of an argument which might be better in an expository essay.
I mean, if I were writing a letter to my Mum after twenty years of not seeing her, I
wouldn't be saying "John Howard's political perspective on asylum seekers at the time made me hate right-wing politics. I thought this lacked humanity. Later on in life I was challenged with Tony Abbot's face on my TV. This made me glad that I had previous hate for John Howard."
The above sentence is very robotic, and establishes things that are true, similar to your sentences.
What would improve this piece is a more realistic representation of Sandra's consciousness (you'd need to have a good deal of empathy for this) and a real nitty-gritty tearing apart of the context. (This is the part that would be better from somebody else because I can't really write a top piece myself). I'll try to write a few sentences that demonstrate what I mean and that hopefully you can see the differences in.
"Ma, I can't describe to you what it feels like to have the legal system against your skin colour. Society against your skin colour. Your family against your skin colour. How could I possibly ask for acceptance for something I couldn't yet accept myself? *I didn't have a choice on friends, groups. I was driven to a place through a lack of other options. I had no idea who I was, I only knew what I had to be to become what I wasn't born into."
(Anyone reading, please don't judge the dodgy writing)
So, the difference I tried to put into that just to reinforce my point (the above writing is by no means classy) is the
a) more human elements.
b) a liiiiitttttle bit more exploration following *. The * hopefully belies the depth of Sandra's predicament, as opposed to "The fact that the black community accepted me, and that my skin colour didn’t have as much relevance to them as it did to ‘whites’ in that era, prompted me to choose to belong to the black community because they shared my values of not caring about skin colour. "
^ Which is a very formulaic sort of response. In that "- blacks accepted me. [fact 1]. they didn't care about my skin colour [fact 2]. They shared my racial tolerance [fact 3].
Urgh. Ask me for clarifications, no doubt you'll need them lol. Sorry if I've just totally confused you.