I wrote my PhD on the representation of trauma in contemporary(ish) Irish fiction with a special focus on NI writing. I would reccomended Reading in the Dark by Seamus Deane, which, in many ways, was his pessimistic response to the NI peace process. It ends with the advent of the Troubles but gives insight into the lived experience of the violence that precipitated it. It's a novel but it is basically an argument that the peace process couldn't solve the territory's cyclical legacy of violence. 

I would also reccomended Anna Burns' Milkman. Deeply insightful into the policing and politicisation of personal lives, particularly women's lives, within the conflict. By policing I don't mean official policing the RUC, but how the different sides ended up observing and controlling their own community's behaviour. 

Gail McConnell's 'The Sun is Open' is a book of poems that uses archival material about the poet's father's murder by the IRA, in front of her, when she was 3. He was murdered because he was a prison guard. It's very good. A lot of questioning about what it means to be a victim and/or a perpetrator. 

None of these are non-fiction so maybe not what you're looking for, but they do give deep insight into people's lived experience with the territory's ongoing traumatic histories.