the She-Devil in the Mirror by Horacio Castellanos Moya (2000)
Olga María is found dead, murdered in front of her children. The daughters think the murderer looks like Robocop. Laura, Olga María’s best friend, can’t understand who’d want to murder her, and she unravels the investigation, Olga María’s secrets and the violent history of El Salvador. 
Because despite the fact that Olga María is the devoted wife and mother, she has had a few affairs. Some Laura knows about and some are revealed to her by the police and the private investigator who is hired by Olga María’s sister.  
This has all the ingredients to be a great book, but the fact that the entire book is a one way conversation between Laura and someone, really ruins it, at least for me. And especially the fact that she says my dear about twice on every page. If only this had been written differently, it would be great.
But this book got me interested in El Salvador’s history. And the fact that this book was from El Salvador is the reason why I finished it and didn’t throw it away.
And what the hell was that last chapter?