The vast majority of the surviving primary sources weren't written by Angolans. But because Portuguese Angola was centered around slave trading, the sources produced by the colony certainly involved Angolans: reports of slaver's raids, counter-attacks by African military leaders, surgeons remarking on slaves' diseases, etc.

Vincent Brown The Reaper's Garden is a great guide to diasporic African folkways surrounding death in the early modern period. He argues that enslaved Africans mobilized their social practices surrounding death as a way of asserting a kind of underground political power in plantation societies. At any rate, you won't find many people studying the history of the Atlantic slave trade or colonial Africa who think that people were coping adequately with the situation. The debate is more about whether it was so shatteringly destructive that it led to a total "social death" or whether some elements of culture and personhood were able to survive. I am in the second camp. But like I said, people were deeply psychologically and often physically scarred in this period.