OP,
Thank you for starting this thread. I've read it all with my heart in my mouth. My father went to boarding school and it had a lifelong traumatic effect on him (he is now in his late sixties). I have heard my father's voice break twice in my life. The first time when he told me about the death of his little brother, who died when he was a child. The second was when he told me about his experiences at boarding school.
This thread has reminded me to always be extra understanding & empathetic towards my father (despite his sometimes difficult behaviour) and mindful of the years of suffering he endured as a child and I want to thank everyone who has shared their experiences here. 
for you all.
OP, to get back to your original post. It resonated with me for several reasons. My DD and DS are now at these exact ages and I am suddenly being sideswiped by my feelings - I totally understand this. I did not go to boarding school, but I had other difficulties in my childhood. It is only now, as an adult, that I am responsible for children who are the same age as I was when I was then (I work as a nanny) that I think FUCK. I was so tiny. I was so vulnerable. I would fight tooth & nail to protect the children I look after from suffering the way I suffered. Where were the adults who were supposed to look after me?
If you've had these feelings and resolved them, how did you do it? I don't want to wallow in this, but I feel I must do something to work through it.
I think there is something profound about caring for a child who is at the age you were when something traumatic happened to you. It really makes you realise something - and you can then work through your feelings and understand your own experience better with hindsight & perspective. It's not wallowing at all - it's healthy & I think it's the best way to avoid passing any of the damage you suffered down to your own children.
Personally, I try not to hold any anger towards my parents (they were doing their best) but I still cry for the little girl I used to be. I wish I could reach back through the years and wrap my arms around that frightened girl and give her a hug.
However, I draw a line between my sadness for the little girl I was, and my happiness as the adult I am now. It's important for my mental health to be able to make that distinction. Someone once told me, when I was crying about my childhood, that the fact I was crying meant I'm not a happy adult because I'm "clearly not over" my childhood. That frustrated me because I didn't have the language to explain myself. I wasn't saying it hasn't affected me, only that I have made peace with all the experiences that have brought me to the person I am today.
I wish I could go back and explain the tears I was shedding weren't for my adult self - they were for the eight year old shaking and vomiting in fear before school.
Sorry for the essay, sorry if all this is totally unhelpful, it's just that making that distinction really helped me to organise some of my thoughts and to feel some of my emotions about my childhood without letting them seep into my adult life.
for you OP.